Re: [PATCH V4 2/2] mmc: sdhci-msm: Use internal voltage control

From: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Vijay Viswanath <vviswana@codeaurora.org>,
	Andy Gross <agross@kernel.org>
Subject: Re: [PATCH V4 2/2] mmc: sdhci-msm: Use internal voltage control
Date: Wed, 17 Jun 2020 18:15:58 +0530	[thread overview]
Message-ID: <40b03630-cdbc-50ee-e483-8ff919f76fb5@codeaurora.org> (raw)
In-Reply-To: <CAPDyKFrvvhQPio3FRQmoBgMm1Euvsma_dgGzxA=R8rm0aQgDMQ@mail.gmail.com>

Thanks for comments Uffe.

On 6/17/2020 3:04 PM, Ulf Hansson wrote:
> On Tue, 16 Jun 2020 at 17:38, Veerabhadrarao Badiganti
> <vbadigan@codeaurora.org> 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.
>>
>> IO-bus supply of eMMC would be kept always-on. So set the load
>> for this supply to configure it in LPM when eMMC is suspend state
>>   and in HPM when eMMC is active.
>>
>> 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>
>> ---
>>   drivers/mmc/host/sdhci-msm.c | 208 +++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 199 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
>> index 15c42b059240..8297b2142748 100644
>> --- a/drivers/mmc/host/sdhci-msm.c
>> +++ b/drivers/mmc/host/sdhci-msm.c
>> @@ -37,7 +37,9 @@
>>   #define CORE_PWRCTL_IO_LOW     BIT(2)
>>   #define CORE_PWRCTL_IO_HIGH    BIT(3)
>>   #define CORE_PWRCTL_BUS_SUCCESS BIT(0)
>> +#define CORE_PWRCTL_BUS_FAIL    BIT(1)
>>   #define CORE_PWRCTL_IO_SUCCESS BIT(2)
>> +#define CORE_PWRCTL_IO_FAIL     BIT(3)
>>   #define REQ_BUS_OFF            BIT(0)
>>   #define REQ_BUS_ON             BIT(1)
>>   #define REQ_IO_LOW             BIT(2)
>> @@ -127,6 +129,9 @@
>>   /* Timeout value to avoid infinite waiting for pwr_irq */
>>   #define MSM_PWR_IRQ_TIMEOUT_MS 5000
>>
>> +/* Max load for eMMC Vdd-io supply */
>> +#define MMC_VQMMC_MAX_LOAD_UA  325000
>> +
>>   #define msm_host_readl(msm_host, host, offset) \
>>          msm_host->var_ops->msm_readl_relaxed(host, offset)
>>
>> @@ -278,6 +283,7 @@ struct sdhci_msm_host {
>>          bool uses_tassadar_dll;
>>          u32 dll_config;
>>          u32 ddr_config;
>> +       bool vqmmc_enabled;
>>   };
>>
>>   static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host)
>> @@ -1346,6 +1352,88 @@ 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)
>> +{
>> +       if (IS_ERR(mmc->supply.vmmc))
>> +               return 0;
>> +
>> +       return mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, mmc->ios.vdd);
>> +}
>> +
>> +static int msm_toggle_vqmmc(struct sdhci_msm_host *msm_host,
>> +                             struct mmc_host *mmc, bool level)
>> +{
>> +       int ret;
>> +       struct mmc_ios ios;
>> +
>> +       if (msm_host->vqmmc_enabled == level)
>> +               return 0;
>> +
>> +       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 msm_config_vqmmc_mode(struct sdhci_msm_host *msm_host,
>> +                             struct mmc_host *mmc, bool hpm)
>> +{
>> +       int load, ret;
>> +
>> +       load = hpm ? MMC_VQMMC_MAX_LOAD_UA : 0;
>> +       ret = regulator_set_load(mmc->supply.vqmmc, load);
>> +       if (ret)
>> +               dev_err(mmc_dev(mmc), "%s: vqmmc set load failed: %d\n",
>> +                       mmc_hostname(mmc), ret);
>> +       return ret;
>> +}
>> +
>> +static int sdhci_msm_set_vqmmc(struct sdhci_msm_host *msm_host,
>> +                             struct mmc_host *mmc, bool level)
>> +{
>> +       int ret;
>> +       bool always_on;
>> +
>> +       if (IS_ERR(mmc->supply.vqmmc)           ||
> White space.
>
>> +           (mmc->ios.power_mode == MMC_POWER_UNDEFINED))
>> +               return 0;
>> +       /*
>> +        * For eMMC don't turn off Vqmmc, Instead just configure it in LPM
>> +        * and HPM modes by setting the right amonut of load.
> /s/right amonut of load/corresponding load
>
>> +        */
>> +       always_on = mmc->card && mmc_card_mmc(mmc->card);
>> +
>> +       if (always_on)
>> +               ret = msm_config_vqmmc_mode(msm_host, mmc, level);
>> +       else
>> +               ret = msm_toggle_vqmmc(msm_host, mmc, level);
> I am worried that this isn't really doing what you think it does.
> always_on may not always be set for an eMMC.
>
> This is because the mmc->card doesn't get assigned until the
> initialization of the eMMC has been completed. In other words, way
> after VCC and VCCQ have been turned on and changed voltage levels.
For the very first time, i have to enable the vqmmc.
And second time on-wards I have to set load instead of turning vqmmc off 
/ on.

This condition helps me in doing exactly the same.

This gets invoked first time when  mmc_power_up() is called.
Yes, by that time card won't be initialized. So this check fails and
allows to turn on the regulator instead of setting load.

After that, this gets invoked only next time mmc_power_up/off() is called
which is during mmc_suspend/resume.

By this time card is initialized, it allows to set load.

> Moreover, mmc_card_mmc() is also about legacy MMC cards, not solely for eMMCs.

Okay. But on qcom platform, we have support for only eMMC/SD/SDIO.
So this mmc_card_mmc() meets my requirements!!! Allows only eMMC not SD 
& SDIO.

> If you want special treatment of an eMMC, I think it's better to use
> the DT bindings Documentation/devicetree/bindings/mmc/mmc-card.txt. If
> you have such a subnode, that indicates that there is an eMMC card
> attached.
>> +
>> +       return ret;
>> +}
>> +
>>   static inline void sdhci_msm_init_pwr_irq_wait(struct sdhci_msm_host *msm_host)
>>   {
>>          init_waitqueue_head(&msm_host->pwr_irq_wait);
>> @@ -1449,8 +1537,9 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
>>   {
>>          struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>          struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
>> +       struct mmc_host *mmc = host->mmc;
>>          u32 irq_status, irq_ack = 0;
>> -       int retry = 10;
>> +       int retry = 10, ret;
>>          u32 pwr_state = 0, io_level = 0;
>>          u32 config;
>>          const struct sdhci_msm_offset *msm_offset = msm_host->offset;
>> @@ -1488,21 +1577,42 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
>>          if (irq_status & CORE_PWRCTL_BUS_ON) {
>>                  pwr_state = REQ_BUS_ON;
>>                  io_level = REQ_IO_HIGH;
>> -               irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
>>          }
>>          if (irq_status & CORE_PWRCTL_BUS_OFF) {
>>                  pwr_state = REQ_BUS_OFF;
>>                  io_level = REQ_IO_LOW;
>> -               irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
>>          }
>> +
>> +       if (pwr_state) {
>> +               ret = sdhci_msm_set_vmmc(mmc);
>> +               if (!ret)
>> +                       ret = sdhci_msm_set_vqmmc(msm_host, mmc,
>> +                                       pwr_state & REQ_BUS_ON);
>> +               if (!ret)
>> +                       irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
>> +               else
>> +                       irq_ack |= CORE_PWRCTL_BUS_FAIL;
>> +       }
>> +
>>          /* Handle IO LOW/HIGH */
>> -       if (irq_status & CORE_PWRCTL_IO_LOW) {
>> +       if (irq_status & CORE_PWRCTL_IO_LOW)
>>                  io_level = REQ_IO_LOW;
>> -               irq_ack |= CORE_PWRCTL_IO_SUCCESS;
>> -       }
>> -       if (irq_status & CORE_PWRCTL_IO_HIGH) {
>> +
>> +       if (irq_status & CORE_PWRCTL_IO_HIGH)
>>                  io_level = REQ_IO_HIGH;
>> +
>> +       if (io_level)
>>                  irq_ack |= CORE_PWRCTL_IO_SUCCESS;
>> +
>> +       if (io_level && !IS_ERR(mmc->supply.vqmmc) && !pwr_state) {
>> +               ret = mmc_regulator_set_vqmmc(mmc, &mmc->ios);
>> +               if (ret < 0) {
>> +                       dev_err(mmc_dev(mmc), "%s: IO_level setting failed(%d). signal_voltage: %d, vdd: %d irq_status: 0x%08x\n",
>> +                                       mmc_hostname(mmc), ret,
>> +                                       mmc->ios.signal_voltage, mmc->ios.vdd,
>> +                                       irq_status);
>> +                       irq_ack |= CORE_PWRCTL_IO_FAIL;
>> +               }
>>          }
>>
>>          /*
>> @@ -1551,7 +1661,7 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
>>          if (io_level)
>>                  msm_host->curr_io_level = io_level;
>>
>> -       pr_debug("%s: %s: Handled IRQ(%d), irq_status=0x%x, ack=0x%x\n",
>> +       dev_dbg(mmc_dev(mmc), "%s: %s: Handled IRQ(%d), irq_status=0x%x, ack=0x%x\n",
>>                  mmc_hostname(msm_host->mmc), __func__, irq, irq_status,
>>                  irq_ack);
>>   }
>> @@ -1881,6 +1991,80 @@ static void sdhci_msm_reset(struct sdhci_host *host, u8 mask)
>>          sdhci_reset(host, mask);
>>   }
>>
>> +static int sdhci_msm_register_vreg(struct sdhci_msm_host *msm_host)
>> +{
>> +       int ret;
>> +       struct mmc_host *mmc = msm_host->mmc;
>> +
>> +       ret = mmc_regulator_get_supply(msm_host->mmc);
>> +       if (ret)
>> +               return ret;
>> +
>> +       sdhci_msm_set_regulator_caps(msm_host);
>> +       mmc->ios.power_mode = MMC_POWER_UNDEFINED;
> The mmc core already sets the initial "power_mode" to
> MMC_POWER_UNDEFINED in mmc_start_host().
>
> If I understand correctly, that may be too late for you. Then, let's
> move that to mmc_alloc_host() instead, rather than having this done
> here.

sure. i will move it to mmc_alloc_host()

>> +
>> +       return 0;
>> +}
>> +
>> +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;
> This looks weird. You probably want to return -EINVAL instead!?
>
>> +       default:
>> +               /* No signal voltage switch required */
>> +               return 0;
> This is an error and should not be treated as a valid case.
> I suggest you return -EINVAL here instead, then you may also skip the
> case for MMC_SIGNAL_VOLTAGE_120 above, as it gets covered in this
> part.

Sure. I will update this.

>> +       }
>> +
>> +       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)
>> +               return 0;
>> +
>> +       dev_warn(mmc_dev(mmc), "%s: Regulator output did not became stable\n",
>> +               mmc_hostname(mmc));
>> +
>> +       return -EAGAIN;
>> +}
>> +
>>   #define DRIVER_NAME "sdhci_msm"
>>   #define SDHCI_MSM_DUMP(f, x...) \
>>          pr_err("%s: " DRIVER_NAME ": " f, mmc_hostname(host->mmc), ## x)
>> @@ -1967,6 +2151,7 @@ void sdhci_msm_dump_vendor_regs(struct sdhci_host *host)
>>          .write_b = sdhci_msm_writeb,
>>          .irq    = sdhci_msm_cqe_irq,
>>          .dump_vendor_regs = sdhci_msm_dump_vendor_regs,
>> +       .set_power = sdhci_set_power_noreg,
>>   };
>>
> [...]
>
> Kind regards
> Uffe
Thanks
Veera