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Commit 56e303eb authored by Wolfgang Muees's avatar Wolfgang Muees Committed by Pierre Ossman
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mmc_spi: convert timeout handling to jiffies and avoid busy waiting 



SD/MMC card timeouts can be very high. So avoid busy-waiting,
using the scheduler. Calculate all timeouts in jiffies units,
because this will give us the correct sign when to involve
the scheduler.

Signed-off-by: default avatarWolfgang Muees <wolfgang.mues@auerswald.de>
Signed-off-by: default avatarPierre Ossman <pierre@ossman.eu>
parent 9d9f25c0

drivers/mmc/host/mmc_spi.c

+21 −17
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ 
 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

#include <linux/hrtimer.h>

#include <linux/sched.h>

#include <linux/delay.h>

#include <linux/bio.h>

#include <linux/dma-mapping.h>
@@ -95,7 +95,7 @@ 
 * reads which takes nowhere near that long.  Older cards may be able to use

 * shorter timeouts ... but why bother?

 */

#define r1b_timeout		ktime_set(3, 0)

#define r1b_timeout		(HZ * 3)





/****************************************************************************/
@@ -183,12 +183,11 @@ mmc_spi_readbytes(struct mmc_spi_host *host, unsigned len) 
	return status;

}



static int

mmc_spi_skip(struct mmc_spi_host *host, ktime_t timeout, unsigned n, u8 byte)

static int mmc_spi_skip(struct mmc_spi_host *host, unsigned long timeout,

			unsigned n, u8 byte)

{

	u8		*cp = host->data->status;



	timeout = ktime_add(timeout, ktime_get());

	unsigned long start = jiffies;



	while (1) {

		int		status;
@@ -203,22 +202,26 @@ mmc_spi_skip(struct mmc_spi_host *host, ktime_t timeout, unsigned n, u8 byte) 
				return cp[i];

		}



		/* REVISIT investigate msleep() to avoid busy-wait I/O

		 * in at least some cases.

		 */

		if (ktime_to_ns(ktime_sub(ktime_get(), timeout)) > 0)

		if (time_is_before_jiffies(start + timeout))

			break;



		/* If we need long timeouts, we may release the CPU.

		 * We use jiffies here because we want to have a relation

		 * between elapsed time and the blocking of the scheduler.

		 */

		if (time_is_before_jiffies(start+1))

			schedule();

	}

	return -ETIMEDOUT;

}



static inline int

mmc_spi_wait_unbusy(struct mmc_spi_host *host, ktime_t timeout)

mmc_spi_wait_unbusy(struct mmc_spi_host *host, unsigned long timeout)

{

	return mmc_spi_skip(host, timeout, sizeof(host->data->status), 0);

}



static int mmc_spi_readtoken(struct mmc_spi_host *host, ktime_t timeout)

static int mmc_spi_readtoken(struct mmc_spi_host *host, unsigned long timeout)

{

	return mmc_spi_skip(host, timeout, 1, 0xff);

}
@@ -607,7 +610,7 @@ mmc_spi_setup_data_message( 
 */

static int

mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,

	ktime_t timeout)

	unsigned long timeout)

{

	struct spi_device	*spi = host->spi;

	int			status, i;
@@ -717,7 +720,7 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t, 
 */

static int

mmc_spi_readblock(struct mmc_spi_host *host, struct spi_transfer *t,

	ktime_t timeout)

	unsigned long timeout)

{

	struct spi_device	*spi = host->spi;

	int			status;
@@ -803,7 +806,7 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct mmc_command *cmd, 
	unsigned		n_sg;

	int			multiple = (data->blocks > 1);

	u32			clock_rate;

	ktime_t			timeout;

	unsigned long		timeout;



	if (data->flags & MMC_DATA_READ)

		direction = DMA_FROM_DEVICE;
@@ -817,8 +820,9 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct mmc_command *cmd, 
	else

		clock_rate = spi->max_speed_hz;



	timeout = ktime_add_ns(ktime_set(0, 0), data->timeout_ns +

			data->timeout_clks * 1000000 / clock_rate);

	timeout = data->timeout_ns +

		  data->timeout_clks * 1000000 / clock_rate;

	timeout = usecs_to_jiffies((unsigned int)(timeout / 1000)) + 1;



	/* Handle scatterlist segments one at a time, with synch for

	 * each 512-byte block