[PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[José Marí­a Fernández González]

From: José M. Fernández <josemariafg@gmail.com>

My working laptop is a Toshiba Tecra M5 with Core2 Duo T7400 and 2GB of
memory. Since I'm using it I have found that some microSD cards (using
their size adapter) are not recognized when they are inserted in the
Tecra M5 SD slot. Now I own one of those cards (a Transcend 2GB
MM8GR02GUACU-PA), which works well with Windows XP and Toshiba drivers.
Looking for a fix I have done some web research about similar laptop
models, and following the clues I found next HTML page:

http://list.drzeus.cx/pipermail/sdhci-devel/2007-December/002089.html

about a kernel patch related to the SD controller in my laptop, which
involves a change on a mmc_delay call on controller startup. The
lspci -vv description for the SD controller is:

06:0b.3 SD Host controller: Texas Instruments PCIxx12 SDA Standard Compliant SD Host Controller (prog-if 01)
        Subsystem: Toshiba America Info Systems Device 0001
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 64 (1750ns min, 1000ns max), Cache Line Size: 32 bytes
        Interrupt: pin D routed to IRQ 23
        Region 0: Memory at ff9ff700 (32-bit, non-prefetchable) [size=256]
        Capabilities: [80] Power Management version 2
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Kernel driver in use: sdhci-pci
        Kernel modules: sdhci-pci

When I applied the proposed change from that patch on mmc_delay
after MMC_POWER_ON, kernel started recognizing the microSD card,
but with errors I have seen with other SD cards:

Feb 21 18:39:25 olympo mmc0: card claims to support voltages below the defined range. These will be ignored.
Feb 21 18:39:25 olympo mmc0: SDIO card claims to support the incompletely defined 'low voltage range'. This will be ignored.
Feb 21 18:39:25 olympo mmc0: error -110 whilst initialising SDIO card

So, I extrapolated the change and, by chance, I found the fix,
which consist on raising the mmc_delay from 2 to 10 both on MMC_POWER_UP
and MMC_POWER_ON. I have been using the kernel with this fix for some
weeks, with no problem.

I don't know whether this patch can break something in the behavior of other
SD controllers, but at least it works for my laptop.

Signed-off-by: José M. Fernández <josemariafg@gmail.com>

---

diff -Nrpu linux-2.6.28.5/drivers/mmc/core/core.c.orig linux-2.6.28.5/drivers/mmc/core/core.c
--- linux-2.6.28.5/drivers/mmc/core/core.c.orig	2009-03-10 01:30:19.000000000 +0100
+++ linux-2.6.28.5/drivers/mmc/core/core.c	2009-03-10 01:29:44.000000000 +0100
@@ -514,7 +514,7 @@ static void mmc_power_up(struct mmc_host
 	 * This delay should be sufficient to allow the power supply
 	 * to reach the minimum voltage.
 	 */
-	mmc_delay(2);
+	mmc_delay(10);
 
 	host->ios.clock = host->f_min;
 	host->ios.power_mode = MMC_POWER_ON;
@@ -524,7 +524,7 @@ static void mmc_power_up(struct mmc_host
 	 * This delay must be at least 74 clock sizes, or 1 ms, or the
 	 * time required to reach a stable voltage.
 	 */
-	mmc_delay(2);
+	mmc_delay(10);
 }
 
 static void mmc_power_off(struct mmc_host *host)

Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[Pierre Ossman]

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On Tue, 10 Mar 2009 02:21:21 +0100
José Marí­a Fernández González <josemariafg@gmail.com> wrote:

> 
> I don't know whether this patch can break something in the behavior of other
> SD controllers, but at least it works for my laptop.
> 

Should be fairly safe, it just slows things down.

> diff -Nrpu linux-2.6.28.5/drivers/mmc/core/core.c.orig linux-2.6.28.5/drivers/mmc/core/core.c
> --- linux-2.6.28.5/drivers/mmc/core/core.c.orig	2009-03-10 01:30:19.000000000 +0100
> +++ linux-2.6.28.5/drivers/mmc/core/core.c	2009-03-10 01:29:44.000000000 +0100
> @@ -514,7 +514,7 @@ static void mmc_power_up(struct mmc_host
>  	 * This delay should be sufficient to allow the power supply
>  	 * to reach the minimum voltage.
>  	 */
> -	mmc_delay(2);
> +	mmc_delay(10);
>  

A delay of 10 is just enough to trigger a sleep on most kernels
(HZ=100). Have you determined the lower bound of these two values?

-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

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Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[José Marí­a Fernández González]

Pierre Ossman wrote:
> On Tue, 10 Mar 2009 02:21:21 +0100
>> diff -Nrpu linux-2.6.28.5/drivers/mmc/core/core.c.orig linux-2.6.28.5/drivers/mmc/core/core.c
>> --- linux-2.6.28.5/drivers/mmc/core/core.c.orig	2009-03-10 01:30:19.000000000 +0100
>> +++ linux-2.6.28.5/drivers/mmc/core/core.c	2009-03-10 01:29:44.000000000 +0100
>> @@ -514,7 +514,7 @@ static void mmc_power_up(struct mmc_host
>>  	 * This delay should be sufficient to allow the power supply
>>  	 * to reach the minimum voltage.
>>  	 */
>> -	mmc_delay(2);
>> +	mmc_delay(10);
>>  
> 
> A delay of 10 is just enough to trigger a sleep on most kernels
> (HZ=100). Have you determined the lower bound of these two values?
> 

Well, I have been using the patch in a kernel with HZ=300, tickless (CONFIG_NO_HZ) and desktop preemption (CONFIG_PREEMPT_VOLUNTARY), but I didn't determine the lower bound. As I explained in the patch at -mm tree, I took as base the patch:

http://list.drzeus.cx/pipermail/sdhci-devel/2007-December/002089.html

and I only extrapolated the need for a higher delay just after MMC_POWER_UP to this one and after MMC_POWER_ON. When I was looking for a fix for the problem I was suffering with my microSD card and laptop, I remember I found some e-mails from two years ago pointing out to some change in the scheduler which uncovered the problem.

As I'm going to install 2.6.29 today, I can test the patch with it and HZ=100.

Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[Pierre Ossman]

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On Wed, 25 Mar 2009 09:00:56 +0100
José Marí­a Fernández González <josemariafg@gmail.com> wrote:

> 
> As I'm going to install 2.6.29 today, I can test the patch with it and HZ=100.

Please do. And try to determine where it breaks. I'd prefer if we don't
need to increase this yet again in a month because we were relying on
some scheduling latencies. :)

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

  WARNING: This correspondence is being monitored by the
  Swedish government. Make sure your server uses encryption
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Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[José Marí­a Fernández González]

Pierre Ossman wrote:
> On Wed, 25 Mar 2009 09:00:56 +0100
> José Marí­a Fernández González <josemariafg@gmail.com> wrote:
> 
>> As I'm going to install 2.6.29 today, I can test the patch with it and HZ=100.
> 
> Please do. And try to determine where it breaks. I'd prefer if we don't
> need to increase this yet again in a month because we were relying on
> some scheduling latencies. :)
> 
> Rgds

I have been testing the patch with kernel 2.6.29 and a couple of cards (the Transcend 2GB microSD and a EZ Memory 8GB SDHC) in a few cases:

*	HZ=300 + tickless + desktop preemption
*	HZ=100 + tickless + desktop preemption
*	HZ=100 + desktop preemption
*	HZ=100 + low latency desktop preemption
*	HZ=1000 + tickless + desktop preemption

and it worked with no problem. I don't know if I have forgotten any obvious corner case. Perhaps I should have tested with no preemption...

	Best Regards,
		José María

Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[Pierre Ossman]

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On Thu, 26 Mar 2009 17:37:10 +0100
José Marí­a Fernández González <josemariafg@gmail.com> wrote:

> Pierre Ossman wrote:
> > On Wed, 25 Mar 2009 09:00:56 +0100
> > José Marí­a Fernández González <josemariafg@gmail.com> wrote:
> > 
> >> As I'm going to install 2.6.29 today, I can test the patch with it and HZ=100.
> > 
> > Please do. And try to determine where it breaks. I'd prefer if we don't
> > need to increase this yet again in a month because we were relying on
> > some scheduling latencies. :)
> > 
> > Rgds
> 
> I have been testing the patch with kernel 2.6.29 and a couple of cards (the Transcend 2GB microSD and a EZ Memory 8GB SDHC) in a few cases:
> 
> *	HZ=300 + tickless + desktop preemption
> *	HZ=100 + tickless + desktop preemption
> *	HZ=100 + desktop preemption
> *	HZ=100 + low latency desktop preemption
> *	HZ=1000 + tickless + desktop preemption
> 
> and it worked with no problem. I don't know if I have forgotten any obvious corner case. Perhaps I should have tested with no preemption...
> 

All of them will result in a sleep though. Preferably, I'd like to now
the minimum delay you need to get things working. Change from
mmc_delay() to mdelay() to make sure there aren't any sleeps (which
generally take quite some time to complete).

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org

  WARNING: This correspondence is being monitored by the
  Swedish government. Make sure your server uses encryption
  for SMTP traffic and consider using PGP for end-to-end
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Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[José Marí­a Fernández González]

It is curious. I have concentrated my tests on 2.6.29 with HZ=100 and no preemption, and I have done next tests with my microSD card and laptop:

*	mmc_delay(2) -> FAIL
*	mdelay(2) -> FAIL
*	mmc_delay(10) -> Works!
*	mdelay(10) -> Works!

And by mistake I found that:

*	msleep(2) -> Works!

	Best Regards,
		José María

Pierre Ossman wrote:
> 
> All of them will result in a sleep though. Preferably, I'd like to now
> the minimum delay you need to get things working. Change from
> mmc_delay() to mdelay() to make sure there aren't any sleeps (which
> generally take quite some time to complete).
> 
> Rgds

Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12 SDA controller

[Pierre Ossman]

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On Tue, 07 Apr 2009 01:30:28 +0200
José Marí­a Fernández González <josemariafg@gmail.com> wrote:

> It is curious. I have concentrated my tests on 2.6.29 with HZ=100 and no preemption, and I have done next tests with my microSD card and laptop:
> 
> *	mmc_delay(2) -> FAIL
> *	mdelay(2) -> FAIL
> *	mmc_delay(10) -> Works!
> *	mdelay(10) -> Works!
> 

Looks good. Although it would have been nice to also know exactly when
it starts working.

> And by mistake I found that:
> 
> *	msleep(2) -> Works!
> 

This is the scheduling effect I was talking about. Basically you can
never get msleep() to delay shorter than 1/HZ seconds.

I'll queue up your patch.

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  rdesktop, core developer          http://www.rdesktop.org
  TigerVNC, core developer          http://www.tigervnc.org

  WARNING: This correspondence is being monitored by the
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