lkml.org 
[lkml]   [2018]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mmc: core: Remove timeout when enabling cache
Date
On some of our boards containing Micron eMMC chips compatible with
the eMMC 5.0 specification we starting seeing boot failures due to
timeouts:
mmc1: error -110 whilst initialising MMC card

It turns out that switching the cache on after a power loss event can
take quite long. In some simple testing thusfar we've seen values up to
700ms, which is far longer then the GENERIC_CMD6_TIME of the chip
(250ms).

Looking at both the eMMC 4.51 and 5.0 specification there doesn't seem
to be a defined upper bound for the CACHE_CTRL ON command. For both
CACHE_CTRL OFF and FLUSH_CACHE it is documented that they can take
essentially unbounded time, but CACHE_CTRL ON i get the impression that
it's assumed to be "fast". Unfortunately this is not true in reality.

To resolve this, simply drop the timeout from CACHE_CTRL ON and assume
it might take an unbounded time similar to the FLUSH_CACHE command.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>

---

drivers/mmc/core/mmc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index bc1bd2c25613..ac70b508a939 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1794,8 +1794,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
if (!mmc_card_broken_hpi(card) &&
card->ext_csd.cache_size > 0) {
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
- EXT_CSD_CACHE_CTRL, 1,
- card->ext_csd.generic_cmd6_time);
+ EXT_CSD_CACHE_CTRL, 1, 0);
if (err && err != -EBADMSG)
goto free_card;

--
2.19.1
\
 
 \ /
  Last update: 2018-11-06 14:31    [W:0.366 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site