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linux/drivers/gpu/drm/drm_dp_helper.c

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/*
* Copyright © 2009 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <drm/drm_dp_helper.h>
#include <drm/drm_print.h>
#include <drm/drm_vblank.h>
#include "drm_crtc_helper_internal.h"
/**
* DOC: dp helpers
*
* These functions contain some common logic and helpers at various abstraction
* levels to deal with Display Port sink devices and related things like DP aux
* channel transfers, EDID reading over DP aux channels, decoding certain DPCD
* blocks, ...
*/
/* Helpers for DP link training */
static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
{
return link_status[r - DP_LANE0_1_STATUS];
}
static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_LANE0_1_STATUS + (lane >> 1);
int s = (lane & 1) * 4;
u8 l = dp_link_status(link_status, i);
return (l >> s) & 0xf;
}
bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
u8 lane_align;
u8 lane_status;
int lane;
lane_align = dp_link_status(link_status,
DP_LANE_ALIGN_STATUS_UPDATED);
if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)
return false;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_channel_eq_ok);
bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
int lane;
u8 lane_status;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if ((lane_status & DP_LANE_CR_DONE) == 0)
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_clock_recovery_ok);
u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage);
u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
DP_TRAINING_AUX_RD_MASK;
if (rd_interval > 4)
DRM_DEBUG_KMS("AUX interval %d, out of range (max 4)\n",
rd_interval);
if (rd_interval == 0 || dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14)
udelay(100);
else
mdelay(rd_interval * 4);
}
EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);
void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
int rd_interval = dpcd[DP_TRAINING_AUX_RD_INTERVAL] &
DP_TRAINING_AUX_RD_MASK;
if (rd_interval > 4)
DRM_DEBUG_KMS("AUX interval %d, out of range (max 4)\n",
rd_interval);
if (rd_interval == 0)
udelay(400);
else
mdelay(rd_interval * 4);
}
EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);
u8 drm_dp_link_rate_to_bw_code(int link_rate)
{
switch (link_rate) {
default:
WARN(1, "unknown DP link rate %d, using %x\n", link_rate,
DP_LINK_BW_1_62);
/* fall through */
case 162000:
return DP_LINK_BW_1_62;
case 270000:
return DP_LINK_BW_2_7;
case 540000:
return DP_LINK_BW_5_4;
case 810000:
return DP_LINK_BW_8_1;
}
}
EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
int drm_dp_bw_code_to_link_rate(u8 link_bw)
{
switch (link_bw) {
default:
WARN(1, "unknown DP link BW code %x, using 162000\n", link_bw);
/* fall through */
case DP_LINK_BW_1_62:
return 162000;
case DP_LINK_BW_2_7:
return 270000;
case DP_LINK_BW_5_4:
return 540000;
case DP_LINK_BW_8_1:
return 810000;
}
}
EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
#define AUX_RETRY_INTERVAL 500 /* us */
static inline void
drm_dp_dump_access(const struct drm_dp_aux *aux,
u8 request, uint offset, void *buffer, int ret)
{
const char *arrow = request == DP_AUX_NATIVE_READ ? "->" : "<-";
if (ret > 0)
DRM_DEBUG_DP("%s: 0x%05x AUX %s (ret=%3d) %*ph\n",
aux->name, offset, arrow, ret, min(ret, 20), buffer);
else
DRM_DEBUG_DP("%s: 0x%05x AUX %s (ret=%3d)\n",
aux->name, offset, arrow, ret);
}
/**
* DOC: dp helpers
*
* The DisplayPort AUX channel is an abstraction to allow generic, driver-
* independent access to AUX functionality. Drivers can take advantage of
* this by filling in the fields of the drm_dp_aux structure.
*
* Transactions are described using a hardware-independent drm_dp_aux_msg
* structure, which is passed into a driver's .transfer() implementation.
* Both native and I2C-over-AUX transactions are supported.
*/
static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
unsigned int offset, void *buffer, size_t size)
{
struct drm_dp_aux_msg msg;
unsigned int retry, native_reply;
int err = 0, ret = 0;
memset(&msg, 0, sizeof(msg));
msg.address = offset;
msg.request = request;
msg.buffer = buffer;
msg.size = size;
mutex_lock(&aux->hw_mutex);
/*
* The specification doesn't give any recommendation on how often to
* retry native transactions. We used to retry 7 times like for
* aux i2c transactions but real world devices this wasn't
* sufficient, bump to 32 which makes Dell 4k monitors happier.
*/
for (retry = 0; retry < 32; retry++) {
if (ret != 0 && ret != -ETIMEDOUT) {
usleep_range(AUX_RETRY_INTERVAL,
AUX_RETRY_INTERVAL + 100);
}
ret = aux->transfer(aux, &msg);
if (ret >= 0) {
native_reply = msg.reply & DP_AUX_NATIVE_REPLY_MASK;
if (native_reply == DP_AUX_NATIVE_REPLY_ACK) {
if (ret == size)
goto unlock;
ret = -EPROTO;
} else
ret = -EIO;
}
/*
* We want the error we return to be the error we received on
* the first transaction, since we may get a different error the
* next time we retry
*/
if (!err)
err = ret;
}
DRM_DEBUG_KMS("Too many retries, giving up. First error: %d\n", err);
ret = err;
unlock:
mutex_unlock(&aux->hw_mutex);
return ret;
}
/**
* drm_dp_dpcd_read() - read a series of bytes from the DPCD
* @aux: DisplayPort AUX channel
* @offset: address of the (first) register to read
* @buffer: buffer to store the register values
* @size: number of bytes in @buffer
*
* Returns the number of bytes transferred on success, or a negative error
* code on failure. -EIO is returned if the request was NAKed by the sink or
* if the retry count was exceeded. If not all bytes were transferred, this
* function returns -EPROTO. Errors from the underlying AUX channel transfer
* function, with the exception of -EBUSY (which causes the transaction to
* be retried), are propagated to the caller.
*/
ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
void *buffer, size_t size)
{
int ret;
/*
* HP ZR24w corrupts the first DPCD access after entering power save
* mode. Eg. on a read, the entire buffer will be filled with the same
* byte. Do a throw away read to avoid corrupting anything we care
* about. Afterwards things will work correctly until the monitor
* gets woken up and subsequently re-enters power save mode.
*
* The user pressing any button on the monitor is enough to wake it
* up, so there is no particularly good place to do the workaround.
* We just have to do it before any DPCD access and hope that the
* monitor doesn't power down exactly after the throw away read.
*/
ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
1);
if (ret != 1)
goto out;
ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
size);
out:
drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, buffer, ret);
return ret;
}
EXPORT_SYMBOL(drm_dp_dpcd_read);
/**
* drm_dp_dpcd_write() - write a series of bytes to the DPCD
* @aux: DisplayPort AUX channel
* @offset: address of the (first) register to write
* @buffer: buffer containing the values to write
* @size: number of bytes in @buffer
*
* Returns the number of bytes transferred on success, or a negative error
* code on failure. -EIO is returned if the request was NAKed by the sink or
* if the retry count was exceeded. If not all bytes were transferred, this
* function returns -EPROTO. Errors from the underlying AUX channel transfer
* function, with the exception of -EBUSY (which causes the transaction to
* be retried), are propagated to the caller.
*/
ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
void *buffer, size_t size)
{
int ret;
ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
size);
drm_dp_dump_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, ret);
return ret;
}
EXPORT_SYMBOL(drm_dp_dpcd_write);
/**
* drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
* @aux: DisplayPort AUX channel
* @status: buffer to store the link status in (must be at least 6 bytes)
*
* Returns the number of bytes transferred on success or a negative error
* code on failure.
*/
int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
u8 status[DP_LINK_STATUS_SIZE])
{
return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
DP_LINK_STATUS_SIZE);
}
EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
/**
* drm_dp_link_probe() - probe a DisplayPort link for capabilities
* @aux: DisplayPort AUX channel
* @link: pointer to structure in which to return link capabilities
*
* The structure filled in by this function can usually be passed directly
* into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
* configure the link based on the link's capabilities.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
u8 values[3];
int err;
memset(link, 0, sizeof(*link));
err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
if (err < 0)
return err;
link->revision = values[0];
link->rate = drm_dp_bw_code_to_link_rate(values[1]);
link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
if (values[2] & DP_ENHANCED_FRAME_CAP)
link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING;
return 0;
}
EXPORT_SYMBOL(drm_dp_link_probe);
/**
* drm_dp_link_power_up() - power up a DisplayPort link
* @aux: DisplayPort AUX channel
* @link: pointer to a structure containing the link configuration
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
u8 value;
int err;
/* DP_SET_POWER register is only available on DPCD v1.1 and later */
if (link->revision < 0x11)
return 0;
err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
if (err < 0)
return err;
value &= ~DP_SET_POWER_MASK;
value |= DP_SET_POWER_D0;
err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
if (err < 0)
return err;
/*
* According to the DP 1.1 specification, a "Sink Device must exit the
* power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
* Control Field" (register 0x600).
*/
usleep_range(1000, 2000);
return 0;
}
EXPORT_SYMBOL(drm_dp_link_power_up);
/**
* drm_dp_link_power_down() - power down a DisplayPort link
* @aux: DisplayPort AUX channel
* @link: pointer to a structure containing the link configuration
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
u8 value;
int err;
/* DP_SET_POWER register is only available on DPCD v1.1 and later */
if (link->revision < 0x11)
return 0;
err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
if (err < 0)
return err;
value &= ~DP_SET_POWER_MASK;
value |= DP_SET_POWER_D3;
err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
if (err < 0)
return err;
return 0;
}
EXPORT_SYMBOL(drm_dp_link_power_down);
/**
* drm_dp_link_configure() - configure a DisplayPort link
* @aux: DisplayPort AUX channel
* @link: pointer to a structure containing the link configuration
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
u8 values[2];
int err;
values[0] = drm_dp_link_rate_to_bw_code(link->rate);
values[1] = link->num_lanes;
if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING)
values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
if (err < 0)
return err;
return 0;
}
EXPORT_SYMBOL(drm_dp_link_configure);
/**
* drm_dp_downstream_max_clock() - extract branch device max
* pixel rate for legacy VGA
* converter or max TMDS clock
* rate for others
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Returns max clock in kHz on success or 0 if max clock not defined
*/
int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DETAILED_CAP_INFO_AVAILABLE;
if (!detailed_cap_info)
return 0;
switch (type) {
case DP_DS_PORT_TYPE_VGA:
return port_cap[1] * 8 * 1000;
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_HDMI:
case DP_DS_PORT_TYPE_DP_DUALMODE:
return port_cap[1] * 2500;
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_clock);
/**
* drm_dp_downstream_max_bpc() - extract branch device max
* bits per component
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
*
* Returns max bpc on success or 0 if max bpc not defined
*/
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4])
{
int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DETAILED_CAP_INFO_AVAILABLE;
int bpc;
if (!detailed_cap_info)
return 0;
switch (type) {
case DP_DS_PORT_TYPE_VGA:
case DP_DS_PORT_TYPE_DVI:
case DP_DS_PORT_TYPE_HDMI:
case DP_DS_PORT_TYPE_DP_DUALMODE:
bpc = port_cap[2] & DP_DS_MAX_BPC_MASK;
switch (bpc) {
case DP_DS_8BPC:
return 8;
case DP_DS_10BPC:
return 10;
case DP_DS_12BPC:
return 12;
case DP_DS_16BPC:
return 16;
}
/* fall through */
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
/**
* drm_dp_downstream_id() - identify branch device
* @aux: DisplayPort AUX channel
* @id: DisplayPort branch device id
*
* Returns branch device id on success or NULL on failure
*/
int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6])
{
return drm_dp_dpcd_read(aux, DP_BRANCH_ID, id, 6);
}
EXPORT_SYMBOL(drm_dp_downstream_id);
/**
* drm_dp_downstream_debug() - debug DP branch devices
* @m: pointer for debugfs file
* @dpcd: DisplayPort configuration data
* @port_cap: port capabilities
* @aux: DisplayPort AUX channel
*
*/
void drm_dp_downstream_debug(struct seq_file *m,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4], struct drm_dp_aux *aux)
{
bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DETAILED_CAP_INFO_AVAILABLE;
int clk;
int bpc;
char id[7];
int len;
uint8_t rev[2];
int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
bool branch_device = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
DP_DWN_STRM_PORT_PRESENT;
seq_printf(m, "\tDP branch device present: %s\n",
branch_device ? "yes" : "no");
if (!branch_device)
return;
switch (type) {
case DP_DS_PORT_TYPE_DP:
seq_puts(m, "\t\tType: DisplayPort\n");
break;
case DP_DS_PORT_TYPE_VGA:
seq_puts(m, "\t\tType: VGA\n");
break;
case DP_DS_PORT_TYPE_DVI:
seq_puts(m, "\t\tType: DVI\n");
break;
case DP_DS_PORT_TYPE_HDMI:
seq_puts(m, "\t\tType: HDMI\n");
break;
case DP_DS_PORT_TYPE_NON_EDID:
seq_puts(m, "\t\tType: others without EDID support\n");
break;
case DP_DS_PORT_TYPE_DP_DUALMODE:
seq_puts(m, "\t\tType: DP++\n");
break;
case DP_DS_PORT_TYPE_WIRELESS:
seq_puts(m, "\t\tType: Wireless\n");
break;
default:
seq_puts(m, "\t\tType: N/A\n");
}
memset(id, 0, sizeof(id));
drm_dp_downstream_id(aux, id);
seq_printf(m, "\t\tID: %s\n", id);
len = drm_dp_dpcd_read(aux, DP_BRANCH_HW_REV, &rev[0], 1);
if (len > 0)
seq_printf(m, "\t\tHW: %d.%d\n",
(rev[0] & 0xf0) >> 4, rev[0] & 0xf);
len = drm_dp_dpcd_read(aux, DP_BRANCH_SW_REV, rev, 2);
if (len > 0)
seq_printf(m, "\t\tSW: %d.%d\n", rev[0], rev[1]);
if (detailed_cap_info) {
clk = drm_dp_downstream_max_clock(dpcd, port_cap);
if (clk > 0) {
if (type == DP_DS_PORT_TYPE_VGA)
seq_printf(m, "\t\tMax dot clock: %d kHz\n", clk);
else
seq_printf(m, "\t\tMax TMDS clock: %d kHz\n", clk);
}
bpc = drm_dp_downstream_max_bpc(dpcd, port_cap);
if (bpc > 0)
seq_printf(m, "\t\tMax bpc: %d\n", bpc);
}
}
EXPORT_SYMBOL(drm_dp_downstream_debug);
/*
* I2C-over-AUX implementation
*/
static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
I2C_FUNC_SMBUS_READ_BLOCK_DATA |
I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
I2C_FUNC_10BIT_ADDR;
}
static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg *msg)
{
/*
* In case of i2c defer or short i2c ack reply to a write,
* we need to switch to WRITE_STATUS_UPDATE to drain the
* rest of the message
*/
if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_I2C_WRITE) {
msg->request &= DP_AUX_I2C_MOT;
msg->request |= DP_AUX_I2C_WRITE_STATUS_UPDATE;
}
}
#define AUX_PRECHARGE_LEN 10 /* 10 to 16 */
#define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */
#define AUX_STOP_LEN 4
#define AUX_CMD_LEN 4
#define AUX_ADDRESS_LEN 20
#define AUX_REPLY_PAD_LEN 4
#define AUX_LENGTH_LEN 8
/*
* Calculate the duration of the AUX request/reply in usec. Gives the
* "best" case estimate, ie. successful while as short as possible.
*/
static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg *msg)
{
int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN +
AUX_CMD_LEN + AUX_ADDRESS_LEN + AUX_LENGTH_LEN;
if ((msg->request & DP_AUX_I2C_READ) == 0)
len += msg->size * 8;
return len;
}
static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg *msg)
{
int len = AUX_PRECHARGE_LEN + AUX_SYNC_LEN + AUX_STOP_LEN +
AUX_CMD_LEN + AUX_REPLY_PAD_LEN;
/*
* For read we expect what was asked. For writes there will
* be 0 or 1 data bytes. Assume 0 for the "best" case.
*/
if (msg->request & DP_AUX_I2C_READ)
len += msg->size * 8;
return len;
}
#define I2C_START_LEN 1
#define I2C_STOP_LEN 1
#define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */
#define I2C_DATA_LEN 9 /* DATA + ACK/NACK */
/*
* Calculate the length of the i2c transfer in usec, assuming
* the i2c bus speed is as specified. Gives the the "worst"
* case estimate, ie. successful while as long as possible.
* Doesn't account the the "MOT" bit, and instead assumes each
* message includes a START, ADDRESS and STOP. Neither does it
* account for additional random variables such as clock stretching.
*/
static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg *msg,
int i2c_speed_khz)
{
/* AUX bitrate is 1MHz, i2c bitrate as specified */
return DIV_ROUND_UP((I2C_START_LEN + I2C_ADDR_LEN +
msg->size * I2C_DATA_LEN +
I2C_STOP_LEN) * 1000, i2c_speed_khz);
}
/*
* Deterine how many retries should be attempted to successfully transfer
* the specified message, based on the estimated durations of the
* i2c and AUX transfers.
*/
static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg *msg,
int i2c_speed_khz)
{
int aux_time_us = drm_dp_aux_req_duration(msg) +
drm_dp_aux_reply_duration(msg);
int i2c_time_us = drm_dp_i2c_msg_duration(msg, i2c_speed_khz);
return DIV_ROUND_UP(i2c_time_us, aux_time_us + AUX_RETRY_INTERVAL);
}
/*
* FIXME currently assumes 10 kHz as some real world devices seem
* to require it. We should query/set the speed via DPCD if supported.
*/
static int dp_aux_i2c_speed_khz __read_mostly = 10;
module_param_unsafe(dp_aux_i2c_speed_khz, int, 0644);
MODULE_PARM_DESC(dp_aux_i2c_speed_khz,
"Assumed speed of the i2c bus in kHz, (1-400, default 10)");
/*
* Transfer a single I2C-over-AUX message and handle various error conditions,
* retrying the transaction as appropriate. It is assumed that the
* &drm_dp_aux.transfer function does not modify anything in the msg other than the
* reply field.
*
* Returns bytes transferred on success, or a negative error code on failure.
*/
static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
{
unsigned int retry, defer_i2c;
int ret;
/*
* DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
* is required to retry at least seven times upon receiving AUX_DEFER
* before giving up the AUX transaction.
*
* We also try to account for the i2c bus speed.
*/
int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
ret = aux->transfer(aux, msg);
if (ret < 0) {
if (ret == -EBUSY)
continue;
/*
* While timeouts can be errors, they're usually normal
* behavior (for instance, when a driver tries to
* communicate with a non-existant DisplayPort device).
* Avoid spamming the kernel log with timeout errors.
*/
if (ret == -ETIMEDOUT)
DRM_DEBUG_KMS_RATELIMITED("transaction timed out\n");
else
DRM_DEBUG_KMS("transaction failed: %d\n", ret);
return ret;
}
switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
case DP_AUX_NATIVE_REPLY_ACK:
/*
* For I2C-over-AUX transactions this isn't enough, we
* need to check for the I2C ACK reply.
*/
break;
case DP_AUX_NATIVE_REPLY_NACK:
DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
return -EREMOTEIO;
case DP_AUX_NATIVE_REPLY_DEFER:
DRM_DEBUG_KMS("native defer\n");
/*
* We could check for I2C bit rate capabilities and if
* available adjust this interval. We could also be
* more careful with DP-to-legacy adapters where a
* long legacy cable may force very low I2C bit rates.
*
* For now just defer for long enough to hopefully be
* safe for all use-cases.
*/
usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
continue;
default:
DRM_ERROR("invalid native reply %#04x\n", msg->reply);
return -EREMOTEIO;
}
switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
case DP_AUX_I2C_REPLY_ACK:
/*
* Both native ACK and I2C ACK replies received. We
* can assume the transfer was successful.
*/
if (ret != msg->size)
drm_dp_i2c_msg_write_status_update(msg);
return ret;
case DP_AUX_I2C_REPLY_NACK:
DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu)\n",
ret, msg->size);
aux->i2c_nack_count++;
return -EREMOTEIO;
case DP_AUX_I2C_REPLY_DEFER:
DRM_DEBUG_KMS("I2C defer\n");
/* DP Compliance Test 4.2.2.5 Requirement:
* Must have at least 7 retries for I2C defers on the
* transaction to pass this test
*/
aux->i2c_defer_count++;
if (defer_i2c < 7)
defer_i2c++;
usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
drm_dp_i2c_msg_write_status_update(msg);
continue;
default:
DRM_ERROR("invalid I2C reply %#04x\n", msg->reply);
return -EREMOTEIO;
}
}
DRM_DEBUG_KMS("too many retries, giving up\n");
return -EREMOTEIO;
}
static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg *msg,
const struct i2c_msg *i2c_msg)
{
msg->request = (i2c_msg->flags & I2C_M_RD) ?
DP_AUX_I2C_READ : DP_AUX_I2C_WRITE;
if (!(i2c_msg->flags & I2C_M_STOP))
msg->request |= DP_AUX_I2C_MOT;
}
/*
* Keep retrying drm_dp_i2c_do_msg until all data has been transferred.
*
* Returns an error code on failure, or a recommended transfer size on success.
*/
static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *orig_msg)
{
int err, ret = orig_msg->size;
struct drm_dp_aux_msg msg = *orig_msg;
while (msg.size > 0) {
err = drm_dp_i2c_do_msg(aux, &msg);
if (err <= 0)
return err == 0 ? -EPROTO : err;
if (err < msg.size && err < ret) {
DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
msg.size, err);
ret = err;
}
msg.size -= err;
msg.buffer += err;
}
return ret;
}
/*
* Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX
* packets to be as large as possible. If not, the I2C transactions never
* succeed. Hence the default is maximum.
*/
static int dp_aux_i2c_transfer_size __read_mostly = DP_AUX_MAX_PAYLOAD_BYTES;
module_param_unsafe(dp_aux_i2c_transfer_size, int, 0644);
MODULE_PARM_DESC(dp_aux_i2c_transfer_size,
"Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)");
static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
int num)
{
struct drm_dp_aux *aux = adapter->algo_data;
unsigned int i, j;
unsigned transfer_size;
struct drm_dp_aux_msg msg;
int err = 0;
dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES);
memset(&msg, 0, sizeof(msg));
for (i = 0; i < num; i++) {
msg.address = msgs[i].addr;
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
/* Send a bare address packet to start the transaction.
* Zero sized messages specify an address only (bare
* address) transaction.
*/
msg.buffer = NULL;
msg.size = 0;
err = drm_dp_i2c_do_msg(aux, &msg);
/*
* Reset msg.request in case in case it got
* changed into a WRITE_STATUS_UPDATE.
*/
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
if (err < 0)
break;
/* We want each transaction to be as large as possible, but
* we'll go to smaller sizes if the hardware gives us a
* short reply.
*/
transfer_size = dp_aux_i2c_transfer_size;
for (j = 0; j < msgs[i].len; j += msg.size) {
msg.buffer = msgs[i].buf + j;
msg.size = min(transfer_size, msgs[i].len - j);
err = drm_dp_i2c_drain_msg(aux, &msg);
/*
* Reset msg.request in case in case it got
* changed into a WRITE_STATUS_UPDATE.
*/
drm_dp_i2c_msg_set_request(&msg, &msgs[i]);
if (err < 0)
break;
transfer_size = err;
}
if (err < 0)
break;
}
if (err >= 0)
err = num;
/* Send a bare address packet to close out the transaction.
* Zero sized messages specify an address only (bare
* address) transaction.
*/
msg.request &= ~DP_AUX_I2C_MOT;
msg.buffer = NULL;
msg.size = 0;
(void)drm_dp_i2c_do_msg(aux, &msg);
return err;
}
static const struct i2c_algorithm drm_dp_i2c_algo = {
.functionality = drm_dp_i2c_functionality,
.master_xfer = drm_dp_i2c_xfer,
};
static struct drm_dp_aux *i2c_to_aux(struct i2c_adapter *i2c)
{
return container_of(i2c, struct drm_dp_aux, ddc);
}
static void lock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
mutex_lock(&i2c_to_aux(i2c)->hw_mutex);
}
static int trylock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
return mutex_trylock(&i2c_to_aux(i2c)->hw_mutex);
}
static void unlock_bus(struct i2c_adapter *i2c, unsigned int flags)
{
mutex_unlock(&i2c_to_aux(i2c)->hw_mutex);
}
static const struct i2c_lock_operations drm_dp_i2c_lock_ops = {
.lock_bus = lock_bus,
.trylock_bus = trylock_bus,
.unlock_bus = unlock_bus,
};
static int drm_dp_aux_get_crc(struct drm_dp_aux *aux, u8 *crc)
{
u8 buf, count;
int ret;
ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf);
if (ret < 0)
return ret;
WARN_ON(!(buf & DP_TEST_SINK_START));
ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK_MISC, &buf);
if (ret < 0)
return ret;
count = buf & DP_TEST_COUNT_MASK;
if (count == aux->crc_count)
return -EAGAIN; /* No CRC yet */
aux->crc_count = count;
/*
* At DP_TEST_CRC_R_CR, there's 6 bytes containing CRC data, 2 bytes
* per component (RGB or CrYCb).
*/
ret = drm_dp_dpcd_read(aux, DP_TEST_CRC_R_CR, crc, 6);
if (ret < 0)
return ret;
return 0;
}
static void drm_dp_aux_crc_work(struct work_struct *work)
{
struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,
crc_work);
struct drm_crtc *crtc;
u8 crc_bytes[6];
uint32_t crcs[3];
int ret;
if (WARN_ON(!aux->crtc))
return;
crtc = aux->crtc;
while (crtc->crc.opened) {
drm_crtc_wait_one_vblank(crtc);
if (!crtc->crc.opened)
break;
ret = drm_dp_aux_get_crc(aux, crc_bytes);
if (ret == -EAGAIN) {
usleep_range(1000, 2000);
ret = drm_dp_aux_get_crc(aux, crc_bytes);
}
if (ret == -EAGAIN) {
DRM_DEBUG_KMS("Get CRC failed after retrying: %d\n",
ret);
continue;
} else if (ret) {
DRM_DEBUG_KMS("Failed to get a CRC: %d\n", ret);
continue;
}
crcs[0] = crc_bytes[0] | crc_bytes[1] << 8;
crcs[1] = crc_bytes[2] | crc_bytes[3] << 8;
crcs[2] = crc_bytes[4] | crc_bytes[5] << 8;
drm_crtc_add_crc_entry(crtc, false, 0, crcs);
}
}
/**
* drm_dp_aux_init() - minimally initialise an aux channel
* @aux: DisplayPort AUX channel
*
* If you need to use the drm_dp_aux's i2c adapter prior to registering it
* with the outside world, call drm_dp_aux_init() first. You must still
* call drm_dp_aux_register() once the connector has been registered to
* allow userspace access to the auxiliary DP channel.
*/
void drm_dp_aux_init(struct drm_dp_aux *aux)
{
mutex_init(&aux->hw_mutex);
mutex_init(&aux->cec.lock);
INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);
aux->ddc.algo = &drm_dp_i2c_algo;
aux->ddc.algo_data = aux;
aux->ddc.retries = 3;
aux->ddc.lock_ops = &drm_dp_i2c_lock_ops;
}
EXPORT_SYMBOL(drm_dp_aux_init);
/**
* drm_dp_aux_register() - initialise and register aux channel
* @aux: DisplayPort AUX channel
*
* Automatically calls drm_dp_aux_init() if this hasn't been done yet.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_aux_register(struct drm_dp_aux *aux)
{
int ret;
if (!aux->ddc.algo)
drm_dp_aux_init(aux);
aux->ddc.class = I2C_CLASS_DDC;
aux->ddc.owner = THIS_MODULE;
aux->ddc.dev.parent = aux->dev;
strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
sizeof(aux->ddc.name));
ret = drm_dp_aux_register_devnode(aux);
if (ret)
return ret;
ret = i2c_add_adapter(&aux->ddc);
if (ret) {
drm_dp_aux_unregister_devnode(aux);
return ret;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_aux_register);
/**
* drm_dp_aux_unregister() - unregister an AUX adapter
* @aux: DisplayPort AUX channel
*/
void drm_dp_aux_unregister(struct drm_dp_aux *aux)
{
drm_dp_aux_unregister_devnode(aux);
i2c_del_adapter(&aux->ddc);
}
EXPORT_SYMBOL(drm_dp_aux_unregister);
#define PSR_SETUP_TIME(x) [DP_PSR_SETUP_TIME_ ## x >> DP_PSR_SETUP_TIME_SHIFT] = (x)
/**
* drm_dp_psr_setup_time() - PSR setup in time usec
* @psr_cap: PSR capabilities from DPCD
*
* Returns:
* PSR setup time for the panel in microseconds, negative
* error code on failure.
*/
int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE])
{
static const u16 psr_setup_time_us[] = {
PSR_SETUP_TIME(330),
PSR_SETUP_TIME(275),
PSR_SETUP_TIME(220),
PSR_SETUP_TIME(165),
PSR_SETUP_TIME(110),
PSR_SETUP_TIME(55),
PSR_SETUP_TIME(0),
};
int i;
i = (psr_cap[1] & DP_PSR_SETUP_TIME_MASK) >> DP_PSR_SETUP_TIME_SHIFT;
if (i >= ARRAY_SIZE(psr_setup_time_us))
return -EINVAL;
return psr_setup_time_us[i];
}
EXPORT_SYMBOL(drm_dp_psr_setup_time);
#undef PSR_SETUP_TIME
/**
* drm_dp_start_crc() - start capture of frame CRCs
* @aux: DisplayPort AUX channel
* @crtc: CRTC displaying the frames whose CRCs are to be captured
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc)
{
u8 buf;
int ret;
ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf);
if (ret < 0)
return ret;
ret = drm_dp_dpcd_writeb(aux, DP_TEST_SINK, buf | DP_TEST_SINK_START);
if (ret < 0)
return ret;
aux->crc_count = 0;
aux->crtc = crtc;
schedule_work(&aux->crc_work);
return 0;
}
EXPORT_SYMBOL(drm_dp_start_crc);
/**
* drm_dp_stop_crc() - stop capture of frame CRCs
* @aux: DisplayPort AUX channel
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_stop_crc(struct drm_dp_aux *aux)
{
u8 buf;
int ret;
ret = drm_dp_dpcd_readb(aux, DP_TEST_SINK, &buf);
if (ret < 0)
return ret;
ret = drm_dp_dpcd_writeb(aux, DP_TEST_SINK, buf & ~DP_TEST_SINK_START);
if (ret < 0)
return ret;
flush_work(&aux->crc_work);
aux->crtc = NULL;
return 0;
}
EXPORT_SYMBOL(drm_dp_stop_crc);
struct dpcd_quirk {
u8 oui[3];
u8 device_id[6];
bool is_branch;
u32 quirks;
};
#define OUI(first, second, third) { (first), (second), (third) }
#define DEVICE_ID(first, second, third, fourth, fifth, sixth) \
{ (first), (second), (third), (fourth), (fifth), (sixth) }
#define DEVICE_ID_ANY DEVICE_ID(0, 0, 0, 0, 0, 0)
static const struct dpcd_quirk dpcd_quirk_list[] = {
/* Analogix 7737 needs reduced M and N at HBR2 link rates */
{ OUI(0x00, 0x22, 0xb9), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
/* LG LP140WF6-SPM1 eDP panel */
{ OUI(0x00, 0x22, 0xb9), DEVICE_ID('s', 'i', 'v', 'a', 'r', 'T'), false, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
/* Apple panels need some additional handling to support PSR */
{ OUI(0x00, 0x10, 0xfa), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_NO_PSR) },
/* CH7511 seems to leave SINK_COUNT zeroed */
{ OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) },
};
#undef OUI
/*
* Get a bit mask of DPCD quirks for the sink/branch device identified by
* ident. The quirk data is shared but it's up to the drivers to act on the
* data.
*
* For now, only the OUI (first three bytes) is used, but this may be extended
* to device identification string and hardware/firmware revisions later.
*/
static u32
drm_dp_get_quirks(const struct drm_dp_dpcd_ident *ident, bool is_branch)
{
const struct dpcd_quirk *quirk;
u32 quirks = 0;
int i;
u8 any_device[] = DEVICE_ID_ANY;
for (i = 0; i < ARRAY_SIZE(dpcd_quirk_list); i++) {
quirk = &dpcd_quirk_list[i];
if (quirk->is_branch != is_branch)
continue;
if (memcmp(quirk->oui, ident->oui, sizeof(ident->oui)) != 0)
continue;
if (memcmp(quirk->device_id, any_device, sizeof(any_device)) != 0 &&
memcmp(quirk->device_id, ident->device_id, sizeof(ident->device_id)) != 0)
continue;
quirks |= quirk->quirks;
}
return quirks;
}
#undef DEVICE_ID_ANY
#undef DEVICE_ID
/**
* drm_dp_read_desc - read sink/branch descriptor from DPCD
* @aux: DisplayPort AUX channel
* @desc: Device decriptor to fill from DPCD
* @is_branch: true for branch devices, false for sink devices
*
* Read DPCD 0x400 (sink) or 0x500 (branch) into @desc. Also debug log the
* identification.
*
* Returns 0 on success or a negative error code on failure.
*/
int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
bool is_branch)
{
struct drm_dp_dpcd_ident *ident = &desc->ident;
unsigned int offset = is_branch ? DP_BRANCH_OUI : DP_SINK_OUI;
int ret, dev_id_len;
ret = drm_dp_dpcd_read(aux, offset, ident, sizeof(*ident));
if (ret < 0)
return ret;
desc->quirks = drm_dp_get_quirks(ident, is_branch);
dev_id_len = strnlen(ident->device_id, sizeof(ident->device_id));
DRM_DEBUG_KMS("DP %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d quirks 0x%04x\n",
is_branch ? "branch" : "sink",
(int)sizeof(ident->oui), ident->oui,
dev_id_len, ident->device_id,
ident->hw_rev >> 4, ident->hw_rev & 0xf,
ident->sw_major_rev, ident->sw_minor_rev,
desc->quirks);
return 0;
}
EXPORT_SYMBOL(drm_dp_read_desc);
/**
* drm_dp_dsc_sink_max_slice_count() - Get the max slice count
* supported by the DSC sink.
* @dsc_dpcd: DSC capabilities from DPCD
* @is_edp: true if its eDP, false for DP
*
* Read the slice capabilities DPCD register from DSC sink to get
* the maximum slice count supported. This is used to populate
* the DSC parameters in the &struct drm_dsc_config by the driver.
* Driver creates an infoframe using these parameters to populate
* &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
* infoframe using the helper function drm_dsc_pps_infoframe_pack()
*
* Returns:
* Maximum slice count supported by DSC sink or 0 its invalid
*/
u8 drm_dp_dsc_sink_max_slice_count(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
bool is_edp)
{
u8 slice_cap1 = dsc_dpcd[DP_DSC_SLICE_CAP_1 - DP_DSC_SUPPORT];
if (is_edp) {
/* For eDP, register DSC_SLICE_CAPABILITIES_1 gives slice count */
if (slice_cap1 & DP_DSC_4_PER_DP_DSC_SINK)
return 4;
if (slice_cap1 & DP_DSC_2_PER_DP_DSC_SINK)
return 2;
if (slice_cap1 & DP_DSC_1_PER_DP_DSC_SINK)
return 1;
} else {
/* For DP, use values from DSC_SLICE_CAP_1 and DSC_SLICE_CAP2 */
u8 slice_cap2 = dsc_dpcd[DP_DSC_SLICE_CAP_2 - DP_DSC_SUPPORT];
if (slice_cap2 & DP_DSC_24_PER_DP_DSC_SINK)
return 24;
if (slice_cap2 & DP_DSC_20_PER_DP_DSC_SINK)
return 20;
if (slice_cap2 & DP_DSC_16_PER_DP_DSC_SINK)
return 16;
if (slice_cap1 & DP_DSC_12_PER_DP_DSC_SINK)
return 12;
if (slice_cap1 & DP_DSC_10_PER_DP_DSC_SINK)
return 10;
if (slice_cap1 & DP_DSC_8_PER_DP_DSC_SINK)
return 8;
if (slice_cap1 & DP_DSC_6_PER_DP_DSC_SINK)
return 6;
if (slice_cap1 & DP_DSC_4_PER_DP_DSC_SINK)
return 4;
if (slice_cap1 & DP_DSC_2_PER_DP_DSC_SINK)
return 2;
if (slice_cap1 & DP_DSC_1_PER_DP_DSC_SINK)
return 1;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_max_slice_count);
/**
* drm_dp_dsc_sink_line_buf_depth() - Get the line buffer depth in bits
* @dsc_dpcd: DSC capabilities from DPCD
*
* Read the DSC DPCD register to parse the line buffer depth in bits which is
* number of bits of precision within the decoder line buffer supported by
* the DSC sink. This is used to populate the DSC parameters in the
* &struct drm_dsc_config by the driver.
* Driver creates an infoframe using these parameters to populate
* &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
* infoframe using the helper function drm_dsc_pps_infoframe_pack()
*
* Returns:
* Line buffer depth supported by DSC panel or 0 its invalid
*/
u8 drm_dp_dsc_sink_line_buf_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
{
u8 line_buf_depth = dsc_dpcd[DP_DSC_LINE_BUF_BIT_DEPTH - DP_DSC_SUPPORT];
switch (line_buf_depth & DP_DSC_LINE_BUF_BIT_DEPTH_MASK) {
case DP_DSC_LINE_BUF_BIT_DEPTH_9:
return 9;
case DP_DSC_LINE_BUF_BIT_DEPTH_10:
return 10;
case DP_DSC_LINE_BUF_BIT_DEPTH_11:
return 11;
case DP_DSC_LINE_BUF_BIT_DEPTH_12:
return 12;
case DP_DSC_LINE_BUF_BIT_DEPTH_13:
return 13;
case DP_DSC_LINE_BUF_BIT_DEPTH_14:
return 14;
case DP_DSC_LINE_BUF_BIT_DEPTH_15:
return 15;
case DP_DSC_LINE_BUF_BIT_DEPTH_16:
return 16;
case DP_DSC_LINE_BUF_BIT_DEPTH_8:
return 8;
}
return 0;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_line_buf_depth);
/**
* drm_dp_dsc_sink_supported_input_bpcs() - Get all the input bits per component
* values supported by the DSC sink.
* @dsc_dpcd: DSC capabilities from DPCD
* @dsc_bpc: An array to be filled by this helper with supported
* input bpcs.
*
* Read the DSC DPCD from the sink device to parse the supported bits per
* component values. This is used to populate the DSC parameters
* in the &struct drm_dsc_config by the driver.
* Driver creates an infoframe using these parameters to populate
* &struct drm_dsc_pps_infoframe. These are sent to the sink using DSC
* infoframe using the helper function drm_dsc_pps_infoframe_pack()
*
* Returns:
* Number of input BPC values parsed from the DPCD
*/
int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
u8 dsc_bpc[3])
{
int num_bpc = 0;
u8 color_depth = dsc_dpcd[DP_DSC_DEC_COLOR_DEPTH_CAP - DP_DSC_SUPPORT];
if (color_depth & DP_DSC_12_BPC)
dsc_bpc[num_bpc++] = 12;
if (color_depth & DP_DSC_10_BPC)
dsc_bpc[num_bpc++] = 10;
if (color_depth & DP_DSC_8_BPC)
dsc_bpc[num_bpc++] = 8;
return num_bpc;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs);
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