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.
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
>
--
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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