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mmc: jz4740: rework pre_req/post_req implementation 

As reported by Aaro, the JZ4740 MMC driver throws a warning when the kernel
is built without preemption (CONFIG_PREEMPT_NONE=y).

[   16.461094] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 567 host->next_data.cookie 568
[   16.473120] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 568 host->next_data.cookie 569
[   16.485144] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 569 host->next_data.cookie 570
[   16.497170] jz4740-mmc 13450000.mmc: [jz4740_mmc_prepare_dma_data] invalid cookie: data->host_cookie 570 host->next_data.cookie 571

The problem seems to be related to how pre_req/post_req is implemented.
Currently, it seems the driver expects jz4740_mmc_prepare_dma_data() to be
called with monotonically increasing host_cookie values, which is wrong.

Moreover, the implementation is overly complicated, keeping track of
unneeded "next cookie" state.

So, instead of attempting to fix the current pre_req/post_req
implementation, this commit refactors the driver, dropping the state,
following other drivers such as dw_mmc and sdhci.

Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Mathieu Malaterre <malat@debian.org>
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Ezequiel Garcia 2018-11-20 15:21:21 -03:00 committed by Ulf Hansson
parent 09b4f70673
commit 96e03fffa3
1 changed files with 54 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

118
drivers/mmc/host/jz4740_mmc.c
View File

@ -126,9 +126,23 @@ enum jz4740_mmc_state {
JZ4740_MMC_STATE_DONE,
};
struct jz4740_mmc_host_next {
int sg_len;
s32 cookie;
/*
* The MMC core allows to prepare a mmc_request while another mmc_request
* is in-flight. This is used via the pre_req/post_req hooks.
* This driver uses the pre_req/post_req hooks to map/unmap the mmc_request.
* Following what other drivers do (sdhci, dw_mmc) we use the following cookie
* flags to keep track of the mmc_request mapping state.
*
* COOKIE_UNMAPPED: the request is not mapped.
* COOKIE_PREMAPPED: the request was mapped in pre_req,
* and should be unmapped in post_req.
* COOKIE_MAPPED: the request was mapped in the irq handler,
* and should be unmapped before mmc_request_done is called..
*/
enum jz4780_cookie {
COOKIE_UNMAPPED = 0,
COOKIE_PREMAPPED,
COOKIE_MAPPED,
};
struct jz4740_mmc_host {
@ -163,9 +177,7 @@ struct jz4740_mmc_host {
/* DMA support */
struct dma_chan *dma_rx;
struct dma_chan *dma_tx;
struct jz4740_mmc_host_next next_data;
bool use_dma;
int sg_len;
/* The DMA trigger level is 8 words, that is to say, the DMA read
* trigger is when data words in MSC_RXFIFO is >= 8 and the DMA write
@ -227,9 +239,6 @@ static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
return PTR_ERR(host->dma_rx);
}
/* Initialize DMA pre request cookie */
host->next_data.cookie = 1;
return 0;
}
@ -246,60 +255,44 @@ static void jz4740_mmc_dma_unmap(struct jz4740_mmc_host *host,
enum dma_data_direction dir = mmc_get_dma_dir(data);
dma_unmap_sg(chan->device->dev, data->sg, data->sg_len, dir);
data->host_cookie = COOKIE_UNMAPPED;
}
/* Prepares DMA data for current/next transfer, returns non-zero on failure */
/* Prepares DMA data for current or next transfer.
* A request can be in-flight when this is called.
*/
static int jz4740_mmc_prepare_dma_data(struct jz4740_mmc_host *host,
struct mmc_data *data,
struct jz4740_mmc_host_next *next,
struct dma_chan *chan)
int cookie)
{
struct jz4740_mmc_host_next *next_data = &host->next_data;
struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
enum dma_data_direction dir = mmc_get_dma_dir(data);
int sg_len;
int sg_count;
if (!next && data->host_cookie &&
data->host_cookie != host->next_data.cookie) {
dev_warn(mmc_dev(host->mmc),
"[%s] invalid cookie: data->host_cookie %d host->next_data.cookie %d\n",
__func__,
data->host_cookie,
host->next_data.cookie);
data->host_cookie = 0;
}
if (data->host_cookie == COOKIE_PREMAPPED)
return data->sg_count;
/* Check if next job is already prepared */
if (next || data->host_cookie != host->next_data.cookie) {
sg_len = dma_map_sg(chan->device->dev,
data->sg,
data->sg_len,
dir);
sg_count = dma_map_sg(chan->device->dev,
data->sg,
data->sg_len,
dir);
} else {
sg_len = next_data->sg_len;
next_data->sg_len = 0;
}
if (sg_len <= 0) {
if (sg_count <= 0) {
dev_err(mmc_dev(host->mmc),
"Failed to map scatterlist for DMA operation\n");
return -EINVAL;
}
if (next) {
next->sg_len = sg_len;
data->host_cookie = ++next->cookie < 0 ? 1 : next->cookie;
} else
host->sg_len = sg_len;
data->sg_count = sg_count;
data->host_cookie = cookie;
return 0;
return data->sg_count;
}
static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
struct mmc_data *data)
{
int ret;
struct dma_chan *chan;
struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
struct dma_async_tx_descriptor *desc;
struct dma_slave_config conf = {
.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
@ -307,29 +300,26 @@ static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
.src_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
.dst_maxburst = JZ4740_MMC_FIFO_HALF_SIZE,
};
int sg_count;
if (data->flags & MMC_DATA_WRITE) {
conf.direction = DMA_MEM_TO_DEV;
conf.dst_addr = host->mem_res->start + JZ_REG_MMC_TXFIFO;
conf.slave_id = JZ4740_DMA_TYPE_MMC_TRANSMIT;
chan = host->dma_tx;
} else {
conf.direction = DMA_DEV_TO_MEM;
conf.src_addr = host->mem_res->start + JZ_REG_MMC_RXFIFO;
conf.slave_id = JZ4740_DMA_TYPE_MMC_RECEIVE;
chan = host->dma_rx;
}
ret = jz4740_mmc_prepare_dma_data(host, data, NULL, chan);
if (ret)
return ret;
sg_count = jz4740_mmc_prepare_dma_data(host, data, COOKIE_MAPPED);
if (sg_count < 0)
return sg_count;
dmaengine_slave_config(chan, &conf);
desc = dmaengine_prep_slave_sg(chan,
data->sg,
host->sg_len,
conf.direction,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
desc = dmaengine_prep_slave_sg(chan, data->sg, sg_count,
conf.direction,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dev_err(mmc_dev(host->mmc),
"Failed to allocate DMA %s descriptor",
@ -343,7 +333,8 @@ static int jz4740_mmc_start_dma_transfer(struct jz4740_mmc_host *host,
return 0;
dma_unmap:
jz4740_mmc_dma_unmap(host, data);
if (data->host_cookie == COOKIE_MAPPED)
jz4740_mmc_dma_unmap(host, data);
return -ENOMEM;
}
@ -352,16 +343,13 @@ static void jz4740_mmc_pre_request(struct mmc_host *mmc,
{
struct jz4740_mmc_host *host = mmc_priv(mmc);
struct mmc_data *data = mrq->data;
struct jz4740_mmc_host_next *next_data = &host->next_data;
BUG_ON(data->host_cookie);
if (!host->use_dma)
return;
if (host->use_dma) {
struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
if (jz4740_mmc_prepare_dma_data(host, data, next_data, chan))
data->host_cookie = 0;
}
data->host_cookie = COOKIE_UNMAPPED;
if (jz4740_mmc_prepare_dma_data(host, data, COOKIE_PREMAPPED) < 0)
data->host_cookie = COOKIE_UNMAPPED;
}
static void jz4740_mmc_post_request(struct mmc_host *mmc,
@ -371,10 +359,8 @@ static void jz4740_mmc_post_request(struct mmc_host *mmc,
struct jz4740_mmc_host *host = mmc_priv(mmc);
struct mmc_data *data = mrq->data;
if (host->use_dma && data->host_cookie) {
if (data && data->host_cookie != COOKIE_UNMAPPED)
jz4740_mmc_dma_unmap(host, data);
data->host_cookie = 0;
}
if (err) {
struct dma_chan *chan = jz4740_mmc_get_dma_chan(host, data);
@ -437,10 +423,14 @@ static void jz4740_mmc_reset(struct jz4740_mmc_host *host)
static void jz4740_mmc_request_done(struct jz4740_mmc_host *host)
{
struct mmc_request *req;
struct mmc_data *data;
req = host->req;
data = req->data;
host->req = NULL;
if (data && data->host_cookie == COOKIE_MAPPED)
jz4740_mmc_dma_unmap(host, data);
mmc_request_done(host->mmc, req);
}