linux-kernel - Re: [PATCH 1/1] mmc: Bad device can cause mmc driver to hang

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Message-ID: <50A71DA5.2070905@linux.vnet.ibm.com>
Date:	Fri, 16 Nov 2012 23:16:21 -0600
From:	Trey Ramsay <tramsay@...ux.vnet.ibm.com>
To:	Chris Ball <cjb@...top.org>
CC:	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
	Rich Rattanni <rattanni@...il.com>,
	Radovan Lekanovic <lekanovic@...il.com>
Subject: Re: [PATCH 1/1] mmc: Bad device can cause mmc driver to hang

On 11/16/2012 06:37 PM, Chris Ball wrote:
> Hi Trey, thanks for the analysis,
> 
> On Fri, Nov 16 2012, Trey Ramsay wrote:
>> Good question.  In regards to the original problem were it was hung in
>> mmc_blk_err_check, the new code path will timeout after 10 minutes, log
>> an error, issue a hardware reset and abort the request. Is the hardware
>> reset enough or will that even work when the device isn't coming out of
>> program state? Should we try to refuse all new I/O?
> 
> mmc_hw_reset() only works for eMMC devices with a hooked up reset GPIO
> -- not SD cards -- and at the moment there's only one system (Intel
> Medfield) that supplies a GPIO, so that's not a general solution.
> 
> Maybe we should just merge your patch for now; we'll definitely get at
> least a pr_err() explaining what's going on, which is an improvement.
> Next time someone hits this (if anyone has an SD card that exhibits
> this problem, it'd be very valuable for testing) we can look at going
> farther, such as immediately setting host->flags |= SDHCI_DEVICE_DEAD.
> What do you think?
> 
> - Chris.
> 

Hi Chris,
Sounds good.  Thanks for the explanation. Setting host->flags |=
SDHCI_DEVICE_DEAD is a great idea.  I'll check with my team to see if we
have any hardware that exhibits this problem.  If we do, I can do some
testing on the code you suggested.

Thanks,
Trey

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