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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 25 Mar 2009 09:00:56 +0100
From:	José María Fernández González 
	<josemariafg@...il.com>
To:	Pierre Ossman <drzeus-list@...eus.cx>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] mmc: Some microSD cards are not recognized by PCIxx12
 SDA controller

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/