Re: [PATCH] mmc: sdhci: ignore 3.3v voltage switch if ios.vdd is 0

[Zhoujie Wu <zjwu@marvell.com>]

Hi Adrian,

On 08/02/2017 12:28 AM, Adrian Hunter wrote:
> On 02/08/17 02:58, Zhoujie Wu 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
> We ought to be able to skip restoring the I/O state when the power is off i.e.:
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index cf2166e4190d..4a70f2f765b6 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2934,7 +2934,8 @@ int sdhci_runtime_resume_host(struct sdhci_host *host)
>
>   	sdhci_init(host, 0);
>
> -	if (mmc->ios.power_mode != MMC_POWER_UNDEFINED) {
> +	if (mmc->ios.power_mode != MMC_POWER_UNDEFINED &&
> +	    mmc->ios.power_mode != MMC_POWER_OFF) {
>   		/* Force clock and power re-program */
>   		host->pwr = 0;
>   		host->clock = 0;

Your suggestion works and better than mine. I will do more tests and 
update the patch later. thanks.
>
>
>> 				-> 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@marvell.com>
>> ---
>> Hi Ulf,
>> 	Not sure if this is the best way to fix it. Please help to suggest. Thanks.
>>
>>   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",
>>