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mmc: fsl_esdhc: increase data transaction timeout to 500ms

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The MMC spec says "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. So, increase the timeout to 500ms.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>
This commit is contained in:
Yangbo Lu 2015-12-30 14:19:30 +08:00 committed by York Sun
parent 335b1936eb
commit e978a31b63
1 changed files with 8 additions and 1 deletions
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9
drivers/mmc/fsl_esdhc.c
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@ -252,8 +252,15 @@ static int esdhc_setup_data(struct mmc *mmc, struct mmc_data *data)
* Rounding up to next power of 2 * Rounding up to next power of 2
* => timeout + 13 = log2(mmc->clock/4) + 1 * => timeout + 13 = log2(mmc->clock/4) + 1
* => timeout + 13 = fls(mmc->clock/4) * => timeout + 13 = fls(mmc->clock/4)
*
* However, 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.
* So, we use
* => timeout + 13 = fls(mmc->clock/2)
*/ */
timeout = fls(mmc->clock/4); timeout = fls(mmc->clock/2);
timeout -= 13; timeout -= 13;
if (timeout > 14) if (timeout > 14)