* [PATCH] mmc: change mmc_delay() to use usleep_range()
@ 2012-01-13 15:09 Dmitry Antipov
2012-01-13 21:38 ` Aaro Koskinen
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry Antipov @ 2012-01-13 15:09 UTC (permalink / raw)
To: Chris Ball; +Cc: patches, linux-mmc, linux-kernel, Dmitry Antipov
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(-)
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);
--
1.7.7.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mmc: change mmc_delay() to use usleep_range()
2012-01-13 15:09 Dmitry Antipov
@ 2012-01-13 21:38 ` Aaro Koskinen
0 siblings, 0 replies; 5+ messages in thread
From: Aaro Koskinen @ 2012-01-13 21:38 UTC (permalink / raw)
To: Dmitry Antipov; +Cc: Chris Ball, patches, linux-mmc, linux-kernel
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.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] mmc: change mmc_delay() to use usleep_range()
@ 2012-01-16 6:43 Dmitry Antipov
2012-01-17 7:29 ` Adrian Hunter
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry Antipov @ 2012-01-16 6:43 UTC (permalink / raw)
To: Chris Ball; +Cc: patches, linux-mmc, linux-kernel, Dmitry Antipov
Use the usleep_range() to simplify mmc_delay() and give some more
accuracy to it - but with an exception of mmc_card_sleepawake():
for the hosts with very small (<100us) sleep/awake timeout, it's
value is rounded up to 100us so usleep_range() always makes sense.
---
drivers/mmc/core/core.h | 8 ++------
drivers/mmc/core/mmc_ops.c | 9 ++++++---
2 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 3bdafbc..fbd2cba 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -48,12 +48,8 @@ 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..457443a 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -82,9 +82,12 @@ 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, which is rounded it up to 100us here. */
+ unsigned long us = DIV_ROUND_UP(card->ext_csd.sa_timeout, 1000);
+ usleep_range(us, us + 100);
+ }
if (!sleep)
err = mmc_select_card(card);
--
1.7.7.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mmc: change mmc_delay() to use usleep_range()
2012-01-16 6:43 [PATCH] mmc: change mmc_delay() to use usleep_range() Dmitry Antipov
@ 2012-01-17 7:29 ` Adrian Hunter
2012-01-17 7:46 ` Adrian Hunter
0 siblings, 1 reply; 5+ messages in thread
From: Adrian Hunter @ 2012-01-17 7:29 UTC (permalink / raw)
To: Dmitry Antipov; +Cc: Chris Ball, patches, linux-mmc, linux-kernel
On 16/01/12 08:43, 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():
> for the hosts with very small (<100us) sleep/awake timeout, it's
> value is rounded up to 100us so usleep_range() always makes sense.
> ---
> drivers/mmc/core/core.h | 8 ++------
> drivers/mmc/core/mmc_ops.c | 9 ++++++---
> 2 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
> index 3bdafbc..fbd2cba 100644
> --- a/drivers/mmc/core/core.h
> +++ b/drivers/mmc/core/core.h
> @@ -48,12 +48,8 @@ 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..457443a 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -82,9 +82,12 @@ 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, which is rounded it up to 100us here. */
> + unsigned long us = DIV_ROUND_UP(card->ext_csd.sa_timeout, 1000);
The divisor has changed from 10000 to 1000 but the change is from ms to us,
so it ought to be 3 zeros different - unless it is a bug fix (which should
be a separate patch)?
> + usleep_range(us, us + 100);
> + }
> if (!sleep)
> err = mmc_select_card(card);
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mmc: change mmc_delay() to use usleep_range()
2012-01-17 7:29 ` Adrian Hunter
@ 2012-01-17 7:46 ` Adrian Hunter
0 siblings, 0 replies; 5+ messages in thread
From: Adrian Hunter @ 2012-01-17 7:46 UTC (permalink / raw)
To: Adrian Hunter
Cc: Dmitry Antipov, Chris Ball, patches, linux-mmc, linux-kernel
On 17/01/12 09:29, Adrian Hunter wrote:
> On 16/01/12 08:43, 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():
>> for the hosts with very small (<100us) sleep/awake timeout, it's
>> value is rounded up to 100us so usleep_range() always makes sense.
>> ---
>> drivers/mmc/core/core.h | 8 ++------
>> drivers/mmc/core/mmc_ops.c | 9 ++++++---
>> 2 files changed, 8 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
>> index 3bdafbc..fbd2cba 100644
>> --- a/drivers/mmc/core/core.h
>> +++ b/drivers/mmc/core/core.h
>> @@ -48,12 +48,8 @@ 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;
A blank line here would be nice
>> + 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..457443a 100644
>> --- a/drivers/mmc/core/mmc_ops.c
>> +++ b/drivers/mmc/core/mmc_ops.c
>> @@ -82,9 +82,12 @@ 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, which is rounded it up to 100us here. */
>> + unsigned long us = DIV_ROUND_UP(card->ext_csd.sa_timeout, 1000);
>
> The divisor has changed from 10000 to 1000 but the change is from ms to us,
> so it ought to be 3 zeros different - unless it is a bug fix (which should
> be a separate patch)?
>
In fact, why not just drop this part of the patch and leave it as mmc_delay?
>> + usleep_range(us, us + 100);
>> + }
>> if (!sleep)
>> err = mmc_select_card(card);
>>
>
> --
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2012-01-16 6:43 [PATCH] mmc: change mmc_delay() to use usleep_range() Dmitry Antipov
2012-01-17 7:29 ` Adrian Hunter
2012-01-17 7:46 ` Adrian Hunter
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2012-01-13 15:09 Dmitry Antipov
2012-01-13 21:38 ` Aaro Koskinen
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