linux-kernel - Re: [PATCH V2 2/3] mmc: sdhci-msm: Use internal voltage control

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Date:   Thu, 21 May 2020 12:07:39 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
Cc:     adrian.hunter@...el.com, ulf.hansson@...aro.org,
        robh+dt@...nel.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, Asutosh Das <asutoshd@...eaurora.org>,
        Vijay Viswanath <vviswana@...eaurora.org>,
        Andy Gross <agross@...nel.org>
Subject: Re: [PATCH V2 2/3] mmc: sdhci-msm: Use internal voltage control

On Thu 21 May 08:23 PDT 2020, Veerabhadrarao Badiganti wrote:

> On qcom SD host controllers voltage switching be done after the HW
> is ready for it. The HW informs its readiness through power irq.
> The voltage switching should happen only then.
> 
> Use the internal voltage switching and then control the voltage
> switching using power irq.
> 
> Set the regulator load as well so that regulator can be configured
> in LPM mode when in is not being used.
> 
> Co-developed-by: Asutosh Das <asutoshd@...eaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> Co-developed-by: Vijay Viswanath <vviswana@...eaurora.org>
> Signed-off-by: Vijay Viswanath <vviswana@...eaurora.org>
> Co-developed-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>

Looks better, thanks.

> ---
>  drivers/mmc/host/sdhci-msm.c | 207 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 198 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
[..]
>  static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host)
> @@ -1298,6 +1302,71 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
>  		sdhci_msm_hs400(host, &mmc->ios);
>  }
>  
> +static int sdhci_msm_set_vmmc(struct mmc_host *mmc)
> +{
> +	int ret;
> +
> +	if (IS_ERR(mmc->supply.vmmc))
> +		return 0;
> +
> +	ret = mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, mmc->ios.vdd);
> +	if (ret)
> +		dev_err(mmc_dev(mmc), "%s: vmmc set ocr with vdd=%d failed: %d\n",
> +			mmc_hostname(mmc), mmc->ios.vdd, ret);

Missed this one on v1, in the event that mmc_regulator_set_ocr() return
a non-zero value it has already printed an error message. So please
replace the tail with just:

	return mmc_regulator_set_ocr(...);

> +
> +	return ret;
> +}
> +
> +static int sdhci_msm_set_vqmmc(struct sdhci_msm_host *msm_host,
> +			      struct mmc_host *mmc, bool level)
> +{
> +	int load, ret;
> +	struct mmc_ios ios;
> +
> +	if (IS_ERR(mmc->supply.vqmmc)			 ||
> +	    (mmc->ios.power_mode == MMC_POWER_UNDEFINED) ||
> +	    (msm_host->vqmmc_enabled == level))
> +		return 0;
> +
> +	if (msm_host->vqmmc_load) {
> +		load = level ? msm_host->vqmmc_load : 0;
> +		ret = regulator_set_load(mmc->supply.vqmmc, load);

Sorry for the late reply on v1, but please see my explanation regarding
load and always-on regulators there.

> +		if (ret) {
> +			dev_err(mmc_dev(mmc), "%s: vqmmc set load failed: %d\n",
> +				mmc_hostname(mmc), ret);
> +			goto out;
> +		}
> +	}
> +
> +	if (level) {
> +		/* Set the IO voltage regulator to default voltage level */
> +		if (msm_host->caps_0 & CORE_3_0V_SUPPORT)
> +			ios.signal_voltage = MMC_SIGNAL_VOLTAGE_330;
> +		else if (msm_host->caps_0 & CORE_1_8V_SUPPORT)
> +			ios.signal_voltage = MMC_SIGNAL_VOLTAGE_180;
> +
> +		if (msm_host->caps_0 & CORE_VOLT_SUPPORT) {
> +			ret = mmc_regulator_set_vqmmc(mmc, &ios);
> +			if (ret < 0) {
> +				dev_err(mmc_dev(mmc), "%s: vqmmc set volgate failed: %d\n",
> +					mmc_hostname(mmc), ret);
> +				goto out;
> +			}
> +		}
> +		ret = regulator_enable(mmc->supply.vqmmc);
> +	} else {
> +		ret = regulator_disable(mmc->supply.vqmmc);
> +	}
> +
> +	if (ret)
> +		dev_err(mmc_dev(mmc), "%s: vqmm %sable failed: %d\n",
> +			mmc_hostname(mmc), level ? "en":"dis", ret);
> +	else
> +		msm_host->vqmmc_enabled = level;
> +out:
> +	return ret;
> +}
[..]
> +static int sdhci_msm_start_signal_voltage_switch(struct mmc_host *mmc,
> +				      struct mmc_ios *ios)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +	u16 ctrl, status;
> +
> +	/*
> +	 * Signal Voltage Switching is only applicable for Host Controllers
> +	 * v3.00 and above.
> +	 */
> +	if (host->version < SDHCI_SPEC_300)
> +		return 0;
> +
> +	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +
> +	switch (ios->signal_voltage) {
> +	case MMC_SIGNAL_VOLTAGE_330:
> +		if (!(host->flags & SDHCI_SIGNALING_330))
> +			return -EINVAL;
> +
> +		/* Set 1.8V Signal Enable in the Host Control2 register to 0 */
> +		ctrl &= ~SDHCI_CTRL_VDD_180;
> +		break;
> +	case MMC_SIGNAL_VOLTAGE_180:
> +		if (!(host->flags & SDHCI_SIGNALING_180))
> +			return -EINVAL;
> +
> +		/*
> +		 * Enable 1.8V Signal Enable in the Host Control2
> +		 * register
> +		 */
> +		ctrl |= SDHCI_CTRL_VDD_180;
> +		break;
> +	case MMC_SIGNAL_VOLTAGE_120:
> +		if (!(host->flags & SDHCI_SIGNALING_120))
> +			return -EINVAL;
> +		return 0;
> +	default:
> +		/* No signal voltage switch required */
> +		return 0;
> +	}
> +
> +	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +
> +	/* Wait for 5ms */
> +	usleep_range(5000, 5500);
> +
> +	/* regulator output should be stable within 5 ms */
> +	status = !!(ctrl & SDHCI_CTRL_VDD_180);
> +	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +	if (!!(ctrl &  SDHCI_CTRL_VDD_180) == status)

You should be able to drop the !! both here and when assigning status.

Overall this looks neater, thanks for reworking it.

Regards,
Bjorn