Re: [PATCH] mmc: use usleep_range() in mmc_delay()
Hi, On Fri, 13 Jan 2012, Dmitry Antipov wrote: On 01/13/2012 05:22 PM, Aaro Koskinen wrote: Anyway, I think the change is good. On systems with multiple MMC devices the boot/probe can spend 100-200 ms alone just doing busylooping delays. I think e.g. in mmc_rescan() the code uses frequently mmc_delay(10). I'm worrying about this: mmc_delay(DIV_ROUND_UP(card->ext_csd.sa_timeout, 1)) since I have no ideas about typical values for this timeout. If it may be too small (<=10 us), using usleep_range() makes no sense. Hmm, but the code above is rounding it up to at least 1 ms? A. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] mmc: use usleep_range() in mmc_delay()
On 01/13/2012 05:22 PM, Aaro Koskinen wrote: Anyway, I think the change is good. On systems with multiple MMC devices the boot/probe can spend 100-200 ms alone just doing busylooping delays. I think e.g. in mmc_rescan() the code uses frequently mmc_delay(10). I'm worrying about this: mmc_delay(DIV_ROUND_UP(card->ext_csd.sa_timeout, 1)) since I have no ideas about typical values for this timeout. If it may be too small (<=10 us), using usleep_range() makes no sense. Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] mmc: use usleep_range() in mmc_delay()
Hi,
On Wed, 21 Dec 2011, Dmitry Antipov wrote:
From f447d78db65c6675e69466e8ed08364ff065ac08 Mon Sep 17 00:00:00 2001
From: Dmitry Antipov
Date: Wed, 21 Dec 2011 10:51:03 +0400
Subject: [PATCH] mmc: use usleep_range() in mmc_delay()
---
Shouldn't you add a proper patch description and a signed-off-by line?
drivers/mmc/core/core.h |8 ++--
1 files changed, 2 insertions(+), 6 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);
}
Anyway, I think the change is good. On systems with multiple MMC devices
the boot/probe can spend 100-200 ms alone just doing busylooping delays. I
think e.g. in mmc_rescan() the code uses frequently mmc_delay(10).
void mmc_rescan(struct work_struct *work);
--
1.7.7.4
A.
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Re: [PATCH] mmc: use usleep_range() in mmc_delay()
Hi Antipov, Sorry for the delayed response. Please find some comments below: On 12/21/2011 6:35 PM, Dmitry Antipov wrote: On 12/21/2011 03:25 PM, Sujit Reddy Thumma wrote: I have posted similar patch some time back. http://comments.gmane.org/gmane.linux.ports.arm.msm/2119. Would you like to comment on that? - I believe we should forget about jiffies, HZ and other similar obsolete timekeeping stuff; - I have no ideas where did you get 'most typical' 20 ms. MMC subsystem uses mmc_delay() with two compile-time fixed values 1 and 10 ms, with the only exception of card-dependent sleep/awake timeout. I was unable to find a table with typical values, but it's rounded up to >= 1 ms anyway. The main aim of my patch was to fix mmc_delay() to give accurate delay. You might want to refer to Documentation/timers/timers-howto.txt (Section: SLEEPING FOR ~USECS OR SMALL MSECS) to know why usleep_range() must be used instead of msleep for delays less than 20ms (or more accurately two jiffies, since in HZ=100 systems this comes to 20ms). Also, in the documentation it is suggested that for delays greater than 10ms+ use msleep(). Although MMC subsystem doesn't use mmc_delay() for greater than 10ms today but I guess we should keep it for future purpose and just not have only usleep_range() as your patch did. Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] mmc: use usleep_range() in mmc_delay()
On 12/21/2011 03:25 PM, Sujit Reddy Thumma wrote: I have posted similar patch some time back. http://comments.gmane.org/gmane.linux.ports.arm.msm/2119. Would you like to comment on that? - I believe we should forget about jiffies, HZ and other similar obsolete timekeeping stuff; - I have no ideas where did you get 'most typical' 20 ms. MMC subsystem uses mmc_delay() with two compile-time fixed values 1 and 10 ms, with the only exception of card-dependent sleep/awake timeout. I was unable to find a table with typical values, but it's rounded up to >= 1 ms anyway. Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] mmc: use usleep_range() in mmc_delay()
On 12/21/2011 12:26 PM, Dmitry Antipov wrote:
From f447d78db65c6675e69466e8ed08364ff065ac08 Mon Sep 17 00:00:00 2001
From: Dmitry Antipov
Date: Wed, 21 Dec 2011 10:51:03 +0400
Subject: [PATCH] mmc: use usleep_range() in mmc_delay()
---
drivers/mmc/core/core.h | 8 ++--
1 files changed, 2 insertions(+), 6 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);
I have posted similar patch some time back.
http://comments.gmane.org/gmane.linux.ports.arm.msm/2119.
Would you like to comment on that?
Thanks,
Sujit
}
void mmc_rescan(struct work_struct *work);
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[PATCH] mmc: use usleep_range() in mmc_delay()
From f447d78db65c6675e69466e8ed08364ff065ac08 Mon Sep 17 00:00:00 2001
From: Dmitry Antipov
Date: Wed, 21 Dec 2011 10:51:03 +0400
Subject: [PATCH] mmc: use usleep_range() in mmc_delay()
---
drivers/mmc/core/core.h |8 ++--
1 files changed, 2 insertions(+), 6 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);
--
1.7.7.4
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