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SubjectRe: [PATCH V1 1/3] mmc: sdhci: Allow platform controlled voltage switching
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Hi Adrian,


On 7/25/2018 5:23 PM, Adrian Hunter wrote:
> On 20/07/18 13:46, Vijay Viswanath wrote:
>> Some controllers can have internal mechanism to inform the SW that it
>> is ready for voltage switching. For such controllers, changing voltage
>> before the HW is ready can result in various issues.
>>
>> During setup/cleanup of host, check whether regulator enable/disable
>> was already done by platform driver.
>>
>> Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
>> ---
>> drivers/mmc/host/sdhci.c | 21 ++++++++++++++++-----
>> 1 file changed, 16 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 1c828e0..494a1e2 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -3472,6 +3472,7 @@ int sdhci_setup_host(struct sdhci_host *host)
>> unsigned int override_timeout_clk;
>> u32 max_clk;
>> int ret;
>> + bool enable_vqmmc = false;
>>
>> WARN_ON(host == NULL);
>> if (host == NULL)
>> @@ -3485,7 +3486,12 @@ int sdhci_setup_host(struct sdhci_host *host)
>> * the host can take the appropriate action if regulators are not
>> * available.
>> */
>> - ret = mmc_regulator_get_supply(mmc);
>> + if (!mmc->supply.vmmc) {
>> + ret = mmc_regulator_get_supply(mmc);
>> + enable_vqmmc = true;
>> + } else {
>> + ret = 0;
>> + }
>> if (ret)
>> return ret;
>
> Why not
>
> if (!mmc->supply.vmmc) {
> ret = mmc_regulator_get_supply(mmc);
> if (ret)
> return ret;
> enable_vqmmc = true;
> }
>

looks neater. Will do.

>>
>> @@ -3736,7 +3742,10 @@ int sdhci_setup_host(struct sdhci_host *host)
>>
>> /* If vqmmc regulator and no 1.8V signalling, then there's no UHS */
>> if (!IS_ERR(mmc->supply.vqmmc)) {
>> - ret = regulator_enable(mmc->supply.vqmmc);
>> + if (enable_vqmmc)
>> + ret = regulator_enable(mmc->supply.vqmmc);
>
> Please introduce host->vqmmc_enabled = !ret;
>

Any reason to introduce vqmmc_enabled variable in sdhci_host structure ?
We can get around with a local variable and using regulator_is_enabled API.

>> + else
>> + ret = 0;
>> if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000,
>> 1950000))
>> host->caps1 &= ~(SDHCI_SUPPORT_SDR104 |
>> @@ -3984,7 +3993,7 @@ int sdhci_setup_host(struct sdhci_host *host)
>> return 0;
>>
>> unreg:
>> - if (!IS_ERR(mmc->supply.vqmmc))
>> + if (!IS_ERR(mmc->supply.vqmmc) && enable_vqmmc)
>
> And just make this
>
> if (host->vqmmc_enabled)
>
>> regulator_disable(mmc->supply.vqmmc);
>> undma:
>> if (host->align_buffer)
>> @@ -4002,7 +4011,8 @@ void sdhci_cleanup_host(struct sdhci_host *host)
>> {
>> struct mmc_host *mmc = host->mmc;
>>
>> - if (!IS_ERR(mmc->supply.vqmmc))
>> + if (!IS_ERR(mmc->supply.vqmmc) &&
>> + (regulator_is_enabled(mmc->supply.vqmmc) > 0))
>
> if (host->vqmmc_enabled)
>
>> regulator_disable(mmc->supply.vqmmc);
>>
>> if (host->align_buffer)
>> @@ -4135,7 +4145,8 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
>>
>> tasklet_kill(&host->finish_tasklet);
>>
>> - if (!IS_ERR(mmc->supply.vqmmc))
>> + if (!IS_ERR(mmc->supply.vqmmc) &&
>> + (regulator_is_enabled(mmc->supply.vqmmc) > 0))
>
> if (host->vqmmc_enabled)
>
>> regulator_disable(mmc->supply.vqmmc);
>>
>> if (host->align_buffer)
>>
>
> --
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>

Thanks,
Vijay

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