mirror of https://gitee.com/openkylin/linux.git
162 lines
3.7 KiB
C
162 lines
3.7 KiB
C
// SPDX-License-Identifier: MIT
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/*
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* Copyright (C) 2013-2019 NVIDIA Corporation
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* Copyright (C) 2015 Rob Clark
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*/
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#include <drm/drm_dp_helper.h>
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#include "dp.h"
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static void drm_dp_link_caps_reset(struct drm_dp_link_caps *caps)
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{
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caps->enhanced_framing = false;
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}
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void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest,
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const struct drm_dp_link_caps *src)
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{
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dest->enhanced_framing = src->enhanced_framing;
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}
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static void drm_dp_link_reset(struct drm_dp_link *link)
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{
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if (!link)
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return;
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link->revision = 0;
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link->max_rate = 0;
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link->max_lanes = 0;
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drm_dp_link_caps_reset(&link->caps);
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link->rate = 0;
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link->lanes = 0;
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}
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/**
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* drm_dp_link_probe() - probe a DisplayPort link for capabilities
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* @aux: DisplayPort AUX channel
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* @link: pointer to structure in which to return link capabilities
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*
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* The structure filled in by this function can usually be passed directly
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* into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
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* configure the link based on the link's capabilities.
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 dpcd[DP_RECEIVER_CAP_SIZE];
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int err;
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drm_dp_link_reset(link);
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err = drm_dp_dpcd_read(aux, DP_DPCD_REV, dpcd, sizeof(dpcd));
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if (err < 0)
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return err;
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link->revision = dpcd[DP_DPCD_REV];
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link->max_rate = drm_dp_max_link_rate(dpcd);
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link->max_lanes = drm_dp_max_lane_count(dpcd);
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link->caps.enhanced_framing = drm_dp_enhanced_frame_cap(dpcd);
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link->rate = link->max_rate;
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link->lanes = link->max_lanes;
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return 0;
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}
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/**
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* drm_dp_link_power_up() - power up a DisplayPort link
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* @aux: DisplayPort AUX channel
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* @link: pointer to a structure containing the link configuration
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 value;
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int err;
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/* DP_SET_POWER register is only available on DPCD v1.1 and later */
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if (link->revision < 0x11)
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return 0;
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err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
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if (err < 0)
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return err;
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value &= ~DP_SET_POWER_MASK;
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value |= DP_SET_POWER_D0;
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err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
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if (err < 0)
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return err;
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/*
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* According to the DP 1.1 specification, a "Sink Device must exit the
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* power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
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* Control Field" (register 0x600).
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*/
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usleep_range(1000, 2000);
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return 0;
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}
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/**
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* drm_dp_link_power_down() - power down a DisplayPort link
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* @aux: DisplayPort AUX channel
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* @link: pointer to a structure containing the link configuration
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 value;
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int err;
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/* DP_SET_POWER register is only available on DPCD v1.1 and later */
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if (link->revision < 0x11)
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return 0;
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err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
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if (err < 0)
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return err;
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value &= ~DP_SET_POWER_MASK;
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value |= DP_SET_POWER_D3;
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err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
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if (err < 0)
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return err;
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return 0;
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}
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/**
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* drm_dp_link_configure() - configure a DisplayPort link
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* @aux: DisplayPort AUX channel
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* @link: pointer to a structure containing the link configuration
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)
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{
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u8 values[2];
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int err;
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values[0] = drm_dp_link_rate_to_bw_code(link->rate);
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values[1] = link->lanes;
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if (link->caps.enhanced_framing)
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values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
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err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
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if (err < 0)
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return err;
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return 0;
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}
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