From 56e303ebeec7ef43dbd9d7998f8ad1a9f75d59bc Mon Sep 17 00:00:00 2001 From: Wolfgang Muees Date: Tue, 7 Apr 2009 15:26:30 +0100 Subject: [PATCH] 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: Wolfgang Muees Signed-off-by: Pierre Ossman --- drivers/mmc/host/mmc_spi.c | 38 +++++++++++++++++++++----------------- 1 file changed, 21 insertions(+), 17 deletions(-) diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c index 72f8bde..ed02ebd 100644 --- a/drivers/mmc/host/mmc_spi.c +++ b/drivers/mmc/host/mmc_spi.c @@ -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 +#include #include #include #include @@ -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 -- 2.7.4