| Message ID | 1326467370-21026-1-git-send-email-dmitry.antipov@linaro.org |
|---|---|
| State | New |
| Headers | show |
Hi, On Fri, 13 Jan 2012, Dmitry Antipov wrote: > Use the usleep_range() to simplify mmc_delay() and give some more > accuracy to it - but with an exception of mmc_card_sleepawake(): > since sleep/awake timeout varies in a wide range, different > delay methods should be used. > > Signed-off-by: Dmitry Antipov <dmitry.antipov@linaro.org> [...] > + if (!(host->caps & MMC_CAP_WAIT_WHILE_BUSY)) { > + /* JEDEC MMCA 4.41 specifies the timeout value is in 200ns..838.86ms > + range. Round it up to 1us and use an appropriate delay method. */ > + unsigned long us = DIV_ROUND_UP(card->ext_csd.sa_timeout, 10); > + if (us < 10) > + udelay(us); > + else > + usleep_range(us, us + 100); > + } I think this part of the patch is over-engineered. What difference does it make in practice if you round it up to a bigger value so that usleep_range() makes always sense? The S/A timeout defines the max time the transition can take, it's not wrong to wait a bit longer. Also note that udelay() is not accurate so you need to add some margin anyway. A.
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h index 14664f1..a77851e 100644 --- a/drivers/mmc/core/core.h +++ b/drivers/mmc/core/core.h @@ -47,12 +47,8 @@ void mmc_power_off(struct mmc_host *host); static inline void mmc_delay(unsigned int ms) { - if (ms < 1000 / HZ) { - cond_resched(); - mdelay(ms); - } else { - msleep(ms); - } + unsigned long us = ms * USEC_PER_MSEC; + usleep_range(us, us + 1000); } void mmc_rescan(struct work_struct *work); diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c index 4d41fa9..38d53ac 100644 --- a/drivers/mmc/core/mmc_ops.c +++ b/drivers/mmc/core/mmc_ops.c @@ -82,9 +82,15 @@ int mmc_card_sleepawake(struct mmc_host *host, int sleep) * SEND_STATUS command to poll the status because that command (and most * others) is invalid while the card sleeps. */ - if (!(host->caps & MMC_CAP_WAIT_WHILE_BUSY)) - mmc_delay(DIV_ROUND_UP(card->ext_csd.sa_timeout, 10000)); - + if (!(host->caps & MMC_CAP_WAIT_WHILE_BUSY)) { + /* JEDEC MMCA 4.41 specifies the timeout value is in 200ns..838.86ms + range. Round it up to 1us and use an appropriate delay method. */ + unsigned long us = DIV_ROUND_UP(card->ext_csd.sa_timeout, 10); + if (us < 10) + udelay(us); + else + usleep_range(us, us + 100); + } if (!sleep) err = mmc_select_card(card);
Use the usleep_range() to simplify mmc_delay() and give some more accuracy to it - but with an exception of mmc_card_sleepawake(): since sleep/awake timeout varies in a wide range, different delay methods should be used. Signed-off-by: Dmitry Antipov <dmitry.antipov@linaro.org> --- drivers/mmc/core/core.h | 8 ++------ drivers/mmc/core/mmc_ops.c | 12 +++++++++--- 2 files changed, 11 insertions(+), 9 deletions(-)