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

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Message-ID: <87mwyh9ia0.fsf@octavius.laptop.org>
Date:	Fri, 16 Nov 2012 19:37:11 -0500
From:	Chris Ball <cjb@...top.org>
To:	Trey Ramsay <tramsay@...ux.vnet.ibm.com>
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

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.
-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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