Hi Gregory,
Thanks for your response.
On 08/02/2017 12:36 AM, Gregory CLEMENT wrote:
Hi Zhoujie, Adrian and Ulf,
On mar., août 01 2017, Zhoujie Wu <zjwu@xxxxxxxxxxx> wrote:
One issue was found on a removable high speed sd card with
runtime pm enabled.
When SD card is unplugged, it keep printing "Switching to 3.3V
signalling voltage failed".
And found below sequence triggers the error.
mmc_rescan
-> mmc_sd_detect
-> mmc_power_off -- mmc->ios.vdd is update to 0.
-> mmc_claim_host
-> sdhci_runtime_resume_host
-> sdhci_start_signal_voltage_switch
-> mmc_regulator_set_vqmmc
-> mmc_ocrbitnum_to_vdd
When mmc_ocrbitnum_to_vdd is called, the mmc->ios.vdd is 0, so it
always return -EINVAL. The signal switch will always fail and
print out warning.
Signed-off-by: Zhoujie Wu <zjwu@xxxxxxxxxxx>
---
Hi Ulf,
Not sure if this is the best way to fix it. Please help to
suggest. Thanks.
I don't know if there is a link, but I observed that when the kernel
boot with an UHS SD Card plugged (and after a warm reset) then the bus
speed is only "High Speed". Whereas if I plugged it while the kernel is
running the "Ultra " speed is detected.
I observed that with the sdhci-xenon driver, but I don't have any other
UHS capable controller available to compare it and to know if it is
something at sdhci level or at xenon level.
I observed the same behavior as you. I added some logs and I found the
difference comes from when init card mmc_sd_get_cid got different ocr
response from SD card.
When boot up board with sd card plugged, SD card ocr response didn't set
S18A bit(bit24 of rocr), so driver won't switch to uhs mode.
[ 4.162597] ocr = 41200000
[ 4.236465] rocr = c0ff8000
If I unplugged the card and plugged it again, this time SD ocr response
set S18A bit(bit24 of rocr), then driver will switch to uhs mode after that.
[ 33.817272] ocr = 41200000
[ 33.920454] rocr = c1ff8000
Currently I have no idea why SD card response different in these two
cases. I will check more details later.
Thanks,
Gregory
drivers/mmc/host/sdhci.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index ecd0d43..011ebbe 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1878,7 +1878,7 @@ int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
ctrl &= ~SDHCI_CTRL_VDD_180;
sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
- if (!IS_ERR(mmc->supply.vqmmc)) {
+ if ((!IS_ERR(mmc->supply.vqmmc)) && mmc->ios.vdd) {
ret = mmc_regulator_set_vqmmc(mmc, ios);
if (ret) {
pr_warn("%s: Switching to 3.3V signalling voltage failed\n",
--
1.9.1
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