Re: [PATCH v1] mmc: sdhci_am654: Add sdhci_am654_start_signal_voltage_switch

[Adrian Hunter]

On 11/09/24 02:22, Judith Mendez wrote:
> Hi Adrian,
> 
> On 9/10/24 12:10 PM, Adrian Hunter wrote:
>> On 10/09/24 17:30, Judith Mendez wrote:
>>> Hi Adrian,
>>>
>>> On 9/9/24 1:26 AM, Adrian Hunter wrote:
>>>> On 6/09/24 20:50, Judith Mendez wrote:
>>>>> The sdhci_start_signal_voltage_switch function sets
>>>>> V1P8_SIGNAL_ENA by default after switching to 1v8 signaling.
>>>>> V1P8_SIGNAL_ENA determines whether to launch cmd/data on neg
>>>>> edge or pos edge of clock.
>>>>>
>>>>> Due to some eMMC and SD failures seen across am62x platform,
>>>>> do not set V1P8_SIGNAL_ENA by default, only enable the bit
>>>>> for devices that require this bit in order to switch to 1v8
>>>>> voltage for uhs modes.
>>>>>
>>>>> Signed-off-by: Judith Mendez <jm@xxxxxx>
>>>>> ---
>>>>>    drivers/mmc/host/sdhci_am654.c | 86 ++++++++++++++++++++++++++++++++++
>>>>>    1 file changed, 86 insertions(+)
>>>>>
>>>>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>>>>> index 0aa3c40ea6ed8..fb6232e56606b 100644
>>>>> --- a/drivers/mmc/host/sdhci_am654.c
>>>>> +++ b/drivers/mmc/host/sdhci_am654.c
>>>>> @@ -155,6 +155,7 @@ struct sdhci_am654_data {
>>>>>        u32 tuning_loop;
>>>>>      #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
>>>>> +#define SDHCI_AM654_QUIRK_SET_V1P8_ENA BIT(1)
>>>>
>>>> It would be better for the quirk to represent the deviation
>>>> from normal i.e.
>>>>
>>>> #define SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA BIT(1)
>>>>
>>>>>    };
>>>>>      struct window {
>>>>> @@ -356,6 +357,79 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
>>>>>        sdhci_set_clock(host, clock);
>>>>>    }
>>>>>    +int sdhci_am654_start_signal_voltage_switch(struct mmc_host *mmc,
>>>>> +                        struct mmc_ios *ios)
>>>>
>>>> Simpler to call sdhci_start_signal_voltage_switch() for the normal
>>>> case e.g.
>>>
>>> This is simpler, so sure will use thanks.
>>>
>>>>
>>>> static int sdhci_am654_start_signal_voltage_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>>>> {
>>>>      struct sdhci_host *host = mmc_priv(mmc);
>>>>      struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>>>      struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
>>>>
>>>>
>>>>      if ((sdhci_am654->quirks & SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA) &&
>>>>          ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
>>>>          ret = mmc_regulator_set_vqmmc(mmc, ios);
>>>>          if (ret < 0) {
>>>>              pr_warn("%s: Switching to 1.8V signalling voltage failed\n",
>>>>                  mmc_hostname(mmc));
>>>>              return -EIO;
>>>>          }
>>>>          return 0;
>>>>      }
>>>>
>>>>      return sdhci_start_signal_voltage_switch(mmc, ios);
>>>> }
>>>>
>>>>> +{
>>>>> +    struct sdhci_host *host = mmc_priv(mmc);
>>>>> +    struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>>>> +    struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
>>>>> +    u16 ctrl;
>>>>> +    int ret;
>>>>> +
>>>>> +    if (host->version < SDHCI_SPEC_300)
>>>>> +        return 0;
>>>>> +
>>>>> +    switch (ios->signal_voltage) {
>>>>> +    case MMC_SIGNAL_VOLTAGE_330:
>>>>> +        if (!(host->flags & SDHCI_SIGNALING_330))
>>>>> +            return -EINVAL;
>>>>> +
>>>>> +        ctrl &= ~SDHCI_CTRL_VDD_180;
>>>>> +        sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
>>>>> +
>>>>> +        if (!IS_ERR(mmc->supply.vqmmc)) {
>>>>> +            ret = mmc_regulator_set_vqmmc(mmc, ios);
>>>>> +            if (ret < 0) {
>>>>> +                pr_warn("%s: Switching to 3.3V signalling voltage failed\n",
>>>>> +                    mmc_hostname(mmc));
>>>>> +                return -EIO;
>>>>> +            }
>>>>> +        }
>>>>> +
>>>>> +        usleep_range(5000, 5500);
>>>>> +
>>>>> +        ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>>>>> +        if (!(ctrl & SDHCI_CTRL_VDD_180))
>>>>> +            return 0;
>>>>> +
>>>>> +        pr_warn("%s: 3.3V regulator output did not become stable\n",
>>>>> +            mmc_hostname(mmc));
>>>>> +
>>>>> +        return -EAGAIN;
>>>>> +
>>>>> +    case MMC_SIGNAL_VOLTAGE_180:
>>>>> +        if (!(host->flags & SDHCI_SIGNALING_180))
>>>>> +            return -EINVAL;
>>>>> +
>>>>> +        if (!IS_ERR(mmc->supply.vqmmc)) {
>>>>> +            ret = mmc_regulator_set_vqmmc(mmc, ios);
>>>>> +            if (ret < 0) {
>>>>> +                pr_warn("%s: Switching to 1.8V signalling voltage failed\n",
>>>>> +                    mmc_hostname(mmc));
>>>>> +                return -EIO;
>>>>> +            }
>>>>> +        }
>>>>> +
>>>>> +        if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_SET_V1P8_ENA) {
>>>>> +            ctrl |= SDHCI_CTRL_VDD_180;
>>>>> +            sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
>>>>> +
>>>>> +            ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>>>>> +            if (ctrl & SDHCI_CTRL_VDD_180)
>>>>> +                return 0;
>>>>> +
>>>>> +            pr_warn("%s: 1.8V regulator output did not become stable\n",
>>>>> +                mmc_hostname(mmc));
>>>>> +
>>>>> +            return -EAGAIN;
>>>>> +        }
>>>>> +        return 0;
>>>>> +
>>>>> +    default:
>>>>> +        return 0;
>>>>> +    }
>>>>> +}
>>>>> +
>>>>>    static u8 sdhci_am654_write_power_on(struct sdhci_host *host, u8 val, int reg)
>>>>>    {
>>>>>        writeb(val, host->ioaddr + reg);
>>>>> @@ -801,6 +875,8 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
>>>>>                        struct sdhci_am654_data *sdhci_am654)
>>>>>    {
>>>>>        struct device *dev = &pdev->dev;
>>>>> +    struct device_node *np = dev->of_node;
>>>>> +    struct device_node *node;
>>>>>        int drv_strength;
>>>>>        int ret;
>>>>>    @@ -844,6 +920,15 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
>>>>>        if (device_property_read_bool(dev, "ti,fails-without-test-cd"))
>>>>>            sdhci_am654->quirks |= SDHCI_AM654_QUIRK_FORCE_CDTEST;
>>>>>    +    node = of_parse_phandle(np, "vmmc-supply", 0);
>>>>> +
>>>>> +    if (node) {
>>>>> +        node = of_parse_phandle(np, "vqmmc-supply", 0);
>>>>> +
>>>>> +        if (!node)
>>>>> +            sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SET_V1P8_ENA;
>>>>> +    }
>>>>
>>>> It would be simpler without 'np' and 'node'.  Not sure
>>>> what the rule is meant to be, but it could be something like:
>>>>
>>>>      if (of_parse_phandle(dev->of_node, "vmmc-supply", 0) &&
>>>>          of_parse_phandle(dev->of_node, "vqmmc-supply", 0)
>>>>          sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA;
>>>
>>> My issue with this is that I also need the quirk (SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA) for eMMC. DT node for eMMC does
>>> not include vmmc and vqmmc supplies. That is why I had the quirk logic
>>> inverted.
>>
>> Ideally there would be a more direct way to distinguish eMMC, but
>> otherwise, having both supplies or neither would be:
>>
>>     if (!!of_parse_phandle(dev->of_node, "vmmc-supply", 0) ==
>>         !!of_parse_phandle(dev->of_node, "vqmmc-supply", 0))
>>         sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA;
> 
> 
> Not sure I love the double NOT, but ok, I can use this, will fix for v2.

It could use a comment, including about the eMMC thing.

> 
> Thanks for your suggestion!
> 
> ~ Judith
> 
>>
>>
>>>
>>> This patch fixes timing issues with both eMMC and SD. (:
>>>
>>> ~ Judith
>>>
>>>
>>>>
>>>>> +
>>>>>        sdhci_get_of_property(pdev);
>>>>>          return 0;
>>>>> @@ -940,6 +1025,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>>>>>            goto err_pltfm_free;
>>>>>        }
>>>>>    +    host->mmc_host_ops.start_signal_voltage_switch = sdhci_am654_start_signal_voltage_switch;
>>>>>        host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>>>>>          pm_runtime_get_noresume(dev);
>>>>>
>>>>> base-commit: cf6444ba528f043398b112ac36e041a4d8685cb1
>>>>
>>>>
>>>
>>
>