We observed the failure of initializing card after resume
accidentally. It's hard to reproduce but we did get report from
the suspend/resume test of our RK3399 mp test farm . Unfortunately,
we still fail to figure out what was going wrong at that time.
Also we can't achieve it by retrying the host->f_init without
falling back it. But this patch will solve the problem as we could
add some log there and see that we resume the mmc card successfully
after falling back the host->f_init.
I believe this is not a specific case for any host controllers as
it's possible the f_init used for this time may fail to init the
mmc for the next booting due to some unexpected signal interference
,etc. Given that, the fallback for host->f_init when booting improve
the robustness. So this should be also beneficial to the resume case,
not just for sloving one specific issue.
[ 93.405085] mmc1: unexpected status 0x800900 after switch
[ 93.408474] mmc1: switch to bus width 1 failed
[ 93.408482] mmc1: mmc_select_hs200 failed, error -110
[ 93.408492] mmc1: error -110 during resume (card was removed?)
[ 93.408705] PM: resume of devices complete after 213.453 msecs
Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
---
Changes in v2:
- remove mmc_power_off
- take f_min into consideration
drivers/mmc/core/mmc.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 3486bc7..06bebc1 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1963,6 +1963,7 @@ static int mmc_suspend(struct mmc_host *host)
static int _mmc_resume(struct mmc_host *host)
{
int err = 0;
+ int i;
BUG_ON(!host);
BUG_ON(!host->card);
@@ -1972,8 +1973,22 @@ static int _mmc_resume(struct mmc_host *host)
if (!mmc_card_suspended(host->card))
goto out;
- mmc_power_up(host, host->card->ocr);
- err = mmc_init_card(host, host->card->ocr, host->card);
+ /*
+ * Let's try to fallback the host->f_init
+ * if failing to init mmc card after resume.
+ */
+ for (i = 0; i < ARRAY_SIZE(freqs); i++) {
+ if (host->f_init < max(freqs[i], host->f_min))
+ continue;
+ else
+ host->f_init = max(freqs[i], host->f_min);
+
+ mmc_power_up(host, host->card->ocr);
+ err = mmc_init_card(host, host->card->ocr, host->card);
+ if (!err)
+ break;
+ }
+
mmc_card_clr_suspended(host->card);
out:
--
2.3.7
--
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