Re: [PATCH V1 1/3] mmc: sdhci: Allow platform controlled voltage switching

[Vijay Viswanath]

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@xxxxxxxxxxxxxx>
> > ---
> >   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