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jmartinccjb
jmartinc
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mmc: mxcmmc: fix bug that may block a data transfer forever
The problem can be easily reproduced using a script that loops copying a file in an SD card to another place in the same SD card and its related to read transfers. This only happens with DMA enabled. This is related to the fact that, when reading, an MMC irq signals the fact that all data from the SD card has been copied to the internal buffers. However, it doesn't signal whether the DMA transfer that is in charge of moving data from these internal buffers to RAM has finished or not. Thus, calling dmaengine_terminate_all() in the MMC irq routine can cancel an ongoing DMA transfer leaving some data in the internal buffers that produces an accumulative effect which, in the end, blocks a read data transfer forever. The following patch watches DMA irq for reading and MMC irqs for writing transfers. The 'dangerous' usage of dmaengine_terminate_all() is removed and a timeout of 10 seconds is added so that the MMC won't block forever anymore. Signed-off-by: Javier Martin <javier.martin@vista-silicon.com> Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Chris Ball <cjb@laptop.org>
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‎drivers/mmc/host/mxcmmc.c

Lines changed: 70 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,7 @@
4444
#include <mach/hardware.h>
4545

4646
#define DRIVER_NAME "mxc-mmc"
47+
#define MXCMCI_TIMEOUT_MS 10000
4748

4849
#define MMC_REG_STR_STP_CLK 0x00
4950
#define MMC_REG_STATUS 0x04
@@ -150,6 +151,8 @@ struct mxcmci_host {
150151
int dmareq;
151152
struct dma_slave_config dma_slave_config;
152153
struct imx_dma_data dma_data;
154+
155+
struct timer_list watchdog;
153156
};
154157

155158
static void mxcmci_set_clk_rate(struct mxcmci_host *host, unsigned int clk_ios);
@@ -271,9 +274,32 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
271274
dmaengine_submit(host->desc);
272275
dma_async_issue_pending(host->dma);
273276

277+
mod_timer(&host->watchdog, jiffies + msecs_to_jiffies(MXCMCI_TIMEOUT_MS));
278+
274279
return 0;
275280
}
276281

282+
static void mxcmci_cmd_done(struct mxcmci_host *host, unsigned int stat);
283+
static void mxcmci_data_done(struct mxcmci_host *host, unsigned int stat);
284+
285+
static void mxcmci_dma_callback(void *data)
286+
{
287+
struct mxcmci_host *host = data;
288+
u32 stat;
289+
290+
del_timer(&host->watchdog);
291+
292+
stat = readl(host->base + MMC_REG_STATUS);
293+
writel(stat & ~STATUS_DATA_TRANS_DONE, host->base + MMC_REG_STATUS);
294+
295+
dev_dbg(mmc_dev(host->mmc), "%s: 0x%08x\n", __func__, stat);
296+
297+
if (stat & STATUS_READ_OP_DONE)
298+
writel(STATUS_READ_OP_DONE, host->base + MMC_REG_STATUS);
299+
300+
mxcmci_data_done(host, stat);
301+
}
302+
277303
static int mxcmci_start_cmd(struct mxcmci_host *host, struct mmc_command *cmd,
278304
unsigned int cmdat)
279305
{
@@ -305,8 +331,14 @@ static int mxcmci_start_cmd(struct mxcmci_host *host, struct mmc_command *cmd,
305331

306332
int_cntr = INT_END_CMD_RES_EN;
307333

308-
if (mxcmci_use_dma(host))
309-
int_cntr |= INT_READ_OP_EN | INT_WRITE_OP_DONE_EN;
334+
if (mxcmci_use_dma(host)) {
335+
if (host->dma_dir == DMA_FROM_DEVICE) {
336+
host->desc->callback = mxcmci_dma_callback;
337+
host->desc->callback_param = host;
338+
} else {
339+
int_cntr |= INT_WRITE_OP_DONE_EN;
340+
}
341+
}
310342

311343
spin_lock_irqsave(&host->lock, flags);
312344
if (host->use_sdio)
@@ -345,11 +377,9 @@ static int mxcmci_finish_data(struct mxcmci_host *host, unsigned int stat)
345377
struct mmc_data *data = host->data;
346378
int data_error;
347379

348-
if (mxcmci_use_dma(host)) {
349-
dmaengine_terminate_all(host->dma);
380+
if (mxcmci_use_dma(host))
350381
dma_unmap_sg(host->dma->device->dev, data->sg, data->sg_len,
351382
host->dma_dir);
352-
}
353383

354384
if (stat & STATUS_ERR_MASK) {
355385
dev_dbg(mmc_dev(host->mmc), "request failed. status: 0x%08x\n",
@@ -624,8 +654,10 @@ static irqreturn_t mxcmci_irq(int irq, void *devid)
624654
mxcmci_cmd_done(host, stat);
625655

626656
if (mxcmci_use_dma(host) &&
627-
(stat & (STATUS_DATA_TRANS_DONE | STATUS_WRITE_OP_DONE)))
657+
(stat & (STATUS_DATA_TRANS_DONE | STATUS_WRITE_OP_DONE))) {
658+
del_timer(&host->watchdog);
628659
mxcmci_data_done(host, stat);
660+
}
629661

630662
if (host->default_irq_mask &&
631663
(stat & (STATUS_CARD_INSERTION | STATUS_CARD_REMOVAL)))
@@ -836,6 +868,34 @@ static bool filter(struct dma_chan *chan, void *param)
836868
return true;
837869
}
838870

871+
static void mxcmci_watchdog(unsigned long data)
872+
{
873+
struct mmc_host *mmc = (struct mmc_host *)data;
874+
struct mxcmci_host *host = mmc_priv(mmc);
875+
struct mmc_request *req = host->req;
876+
unsigned int stat = readl(host->base + MMC_REG_STATUS);
877+
878+
if (host->dma_dir == DMA_FROM_DEVICE) {
879+
dmaengine_terminate_all(host->dma);
880+
dev_err(mmc_dev(host->mmc),
881+
"%s: read time out (status = 0x%08x)\n",
882+
__func__, stat);
883+
} else {
884+
dev_err(mmc_dev(host->mmc),
885+
"%s: write time out (status = 0x%08x)\n",
886+
__func__, stat);
887+
mxcmci_softreset(host);
888+
}
889+
890+
/* Mark transfer as erroneus and inform the upper layers */
891+
892+
host->data->error = -ETIMEDOUT;
893+
host->req = NULL;
894+
host->cmd = NULL;
895+
host->data = NULL;
896+
mmc_request_done(host->mmc, req);
897+
}
898+
839899
static const struct mmc_host_ops mxcmci_ops = {
840900
.request = mxcmci_request,
841901
.set_ios = mxcmci_set_ios,
@@ -968,6 +1028,10 @@ static int mxcmci_probe(struct platform_device *pdev)
9681028

9691029
mmc_add_host(mmc);
9701030

1031+
init_timer(&host->watchdog);
1032+
host->watchdog.function = &mxcmci_watchdog;
1033+
host->watchdog.data = (unsigned long)mmc;
1034+
9711035
return 0;
9721036

9731037
out_free_irq:

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