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SubjectRe: [PATCH V2 2/3] mmc: sdhci-msm: Use internal voltage control
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Hi Bjorn,

On 5/22/2020 12:37 AM, Bjorn Andersson wrote:
> 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@codeaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
>> Co-developed-by: Vijay Viswanath <vviswana@codeaurora.org>
>> Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
>> Co-developed-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
>> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.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.

<Merging your comment from V1 here>

>> You should still call regulator_enable()/regulator_disable() on your
>> consumer regulator in this driver. When you do this the regulator core
>> will conclude that the regulator_dev (i.e. the part that represents the
>> hardware) is marked always_on and will not enable/disable the regulator.

>> But it will still invoke _regulator_handle_consumer_enable() and
>> _regulator_handle_consumer_disable(), which will aggregate the "load" of
>> all client regulators and update the regulator's load.

>> So this will apply the load as you expect regardless of it being
>> supplied by a regulator marked as always_on.

Since I'm not turning off this regulator for eMMC, I wanted to keep it
in LPM mode
to save some power.
When the regulator configured in auto mode (RPMH_REGULATOR_MODE_AUTO) it
switches to LPM/HPM mode based on the active load.
So i have to minimize my driver load requirement so that I can let this
regulator
in LPM mode.
So i need to set load every-time I disable/enable the regulator.

>> + 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


Thanks

Veera

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