Some eMMC will fail at the first switch, but would succeed in a subsequent one.
Make sure we try several times to cover those cases. The number of retries (and the behaviour) is currently what is being used in Linux.
Signed-off-by: Maxime Ripard maxime.ripard@free-electrons.com --- drivers/mmc/mmc.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index 4380c7c195a6..d6b7e4f510c9 100644 --- a/drivers/mmc/mmc.c +++ b/drivers/mmc/mmc.c @@ -494,6 +494,7 @@ int mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value) { struct mmc_cmd cmd; int timeout = 1000; + int retries = 3; int ret;
cmd.cmdidx = MMC_CMD_SWITCH; @@ -502,11 +503,17 @@ int mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value) (index << 16) | (value << 8);
- ret = mmc_send_cmd(mmc, &cmd, NULL); + while (retries > 0) { + ret = mmc_send_cmd(mmc, &cmd, NULL);
- /* Waiting for the ready status */ - if (!ret) - ret = mmc_send_status(mmc, timeout); + /* Waiting for the ready status */ + if (!ret) { + ret = mmc_send_status(mmc, timeout); + return ret; + } + + retries--; + }
return ret;