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mmc: use really long write timeout to deal with crappy cards

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Several people have noticed that crappy SD cards take much longer to
complete multiple block writes than the 300ms that Linux specifies.
Try to work around this by using a three second write timeout instead.

This is a generalized version of a patch from Chase Maupin
<Chase.Maupin@ti.com>, whose patch description said:

* With certain SD cards timeouts like the following have been seen
  due to an improper calculation of the dto value:
    mmcblk0: error -110 transferring data, sector 4126233, nr 8,
    card status 0xc00
* By removing the dto calculation and setting the timeout value
  to the maximum specified by the SD card specification part A2
  section 2.2.15 these timeouts can be avoided.
* This change has been used by beagleboard users as well as the
  Texas Instruments SDK without a negative impact.
* There are multiple discussion threads about this but the most
  relevant ones are:
    * http://talk.maemo.org/showthread.php?p=1000707#post1000707
    * http://www.mail-archive.com/linux-omap@vger.kernel.org/msg42213.html
* Original proposal for this fix was done by Sukumar Ghoral of
  Texas Instruments
* Tested using a Texas Instruments AM335x EVM

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Paul Walmsley 2012-03-12 04:58:00 -06:00 committed by Chris Ball
parent 8c2fc8e413
commit 3bdc9ba892
1 changed files with 7 additions and 3 deletions
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10
drivers/mmc/core/core.c
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@ -527,10 +527,14 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
if (data->flags & MMC_DATA_WRITE)
/*
* The limit is really 250 ms, but that is
* insufficient for some crappy cards.
* The MMC spec "It is strongly recommended
* for hosts to implement more than 500ms
* timeout value even if the card indicates
* the 250ms maximum busy length." Even the
* previous value of 300ms is known to be
* insufficient for some cards.
*/
limit_us = 300000;
limit_us = 3000000;
else
limit_us = 100000;