Re: [PATCH RFC 1/2] mmc: sdhci: Allow platform controlled voltage switching

[Adrian Hunter]

On 17/07/18 12:45, Vijay Viswanath wrote:
> 
> 
> On 7/17/2018 2:12 PM, Adrian Hunter wrote:
>> On 17/07/18 11:40, Vijay Viswanath wrote:
>>>
>>>
>>> On 7/17/2018 1:00 PM, Adrian Hunter wrote:
>>>> On 17/07/18 08:14, Vijay Viswanath wrote:
>>>>>
>>>>>
>>>>> On 7/10/2018 4:37 PM, Adrian Hunter wrote:
>>>>>> On 21/06/18 15:23, 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.
>>>>>>>
>>>>>>> Add a quirk, which can be used by drivers of such controllers.
>>>>>>>
>>>>>>> Signed-off-by: Vijay Viswanath <vviswana@xxxxxxxxxxxxxx>
>>>>>>> ---
>>>>>>> ÂÂÂ drivers/mmc/host/sdhci.c | 20 +++++++++++++++-----
>>>>>>> ÂÂÂ drivers/mmc/host/sdhci.h |Â 2 ++
>>>>>>> ÂÂÂ 2 files changed, 17 insertions(+), 5 deletions(-)
>>>>>>>
>>>>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>>>>> index 1c828e0..f0346d4 100644
>>>>>>> --- a/drivers/mmc/host/sdhci.c
>>>>>>> +++ b/drivers/mmc/host/sdhci.c
>>>>>>> @@ -1615,7 +1615,8 @@ void sdhci_set_power_noreg(struct sdhci_host
>>>>>>> *host,
>>>>>>> unsigned char mode,
>>>>>>> ÂÂÂ void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ unsigned short vdd)
>>>>>>> ÂÂÂ {
>>>>>>> -ÂÂÂ if (IS_ERR(host->mmc->supply.vmmc))
>>>>>>> +ÂÂÂ if (IS_ERR(host->mmc->supply.vmmc) ||
>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂ (host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>>>>>>
>>>>>> I think you should provide your own ->set_power() instead of this
>>>>>>
>>>>>
>>>>> will do
>>>>>
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ sdhci_set_power_noreg(host, mode, vdd);
>>>>>>> ÂÂÂÂÂÂÂ else
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ sdhci_set_power_reg(host, mode, vdd);
>>>>>>> @@ -2009,7 +2010,9 @@ int sdhci_start_signal_voltage_switch(struct
>>>>>>> mmc_host *mmc,
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ ctrl &= ~SDHCI_CTRL_VDD_180;
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
>>>>>>> ÂÂÂ -ÂÂÂÂÂÂÂ if (!IS_ERR(mmc->supply.vqmmc)) {
>>>>>>> +ÂÂÂÂÂÂÂ if (!IS_ERR(mmc->supply.vqmmc) &&
>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ !(host->quirks2 &
>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ SDHCI_QUIRK2_INTERNAL_PWR_CTL)) {
>>>>>>
>>>>>> And your own ->start_signal_voltage_switch()
>>>>>>
>>>>>
>>>>> sdhci_msm_start_signal_voltage_switch() would be an exact copy of
>>>>> sdhci_start_signal_voltage_switch()..... will incorporate this if not
>>>>> using
>>>>> quirk.
>>>>>
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ret = mmc_regulator_set_vqmmc(mmc, ios);
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ if (ret) {
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pr_warn("%s: Switching to 3.3V signalling voltage
>>>>>>> failed\n",
>>>>>>> @@ -2032,7 +2035,8 @@ int sdhci_start_signal_voltage_switch(struct
>>>>>>> mmc_host *mmc,
>>>>>>> ÂÂÂÂÂÂÂ case MMC_SIGNAL_VOLTAGE_180:
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ if (!(host->flags & SDHCI_SIGNALING_180))
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return -EINVAL;
>>>>>>> -ÂÂÂÂÂÂÂ if (!IS_ERR(mmc->supply.vqmmc)) {
>>>>>>> +ÂÂÂÂÂÂÂ if (!IS_ERR(mmc->supply.vqmmc) &&
>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂ !(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL)) {
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ret = mmc_regulator_set_vqmmc(mmc, ios);
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ if (ret) {
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pr_warn("%s: Switching to 1.8V signalling voltage
>>>>>>> failed\n",
>>>>>>> @@ -3485,7 +3489,10 @@ int sdhci_setup_host(struct sdhci_host *host)
>>>>>>> ÂÂÂÂÂÂÂÂ * the host can take the appropriate action if regulators are
>>>>>>> not
>>>>>>> ÂÂÂÂÂÂÂÂ * available.
>>>>>>> ÂÂÂÂÂÂÂÂ */
>>>>>>> -ÂÂÂ ret = mmc_regulator_get_supply(mmc);
>>>>>>> +ÂÂÂ if (!(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>>>>>>
>>>>>> Since we expect mmc_regulator_get_supply() to have been called, this
>>>>>> could
>>>>>> be:
>>>>>>
>>>>>> ÂÂÂÂÂÂif (!mmc->supply.vmmc) {
>>>>>> ÂÂÂÂÂÂÂÂÂ ret = mmc_regulator_get_supply(mmc);
>>>>>> ÂÂÂÂÂÂÂÂÂ enable_vqmmc = true;
>>>>>> ÂÂÂÂÂÂ} else {
>>>>>> ÂÂÂÂÂÂÂÂÂ ret = 0;
>>>>>> ÂÂÂÂÂÂ}
>>>>>>>> +ÂÂÂÂÂÂÂ ret = mmc_regulator_get_supply(mmc);
>>>>>>> +ÂÂÂ else
>>>>>>> +ÂÂÂÂÂÂÂ ret = 0;
>>>>>>> ÂÂÂÂÂÂÂ if (ret)
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ return ret;
>>>>>>> ÂÂÂ @@ -3736,7 +3743,10 @@ int sdhci_setup_host(struct sdhci_host *host)
>>>>>>> ÂÂÂ ÂÂÂÂÂ /* If vqmmc regulator and no 1.8V signalling, then there's no
>>>>>>> UHS */
>>>>>>> ÂÂÂÂÂÂÂ if (!IS_ERR(mmc->supply.vqmmc)) {
>>>>>>> -ÂÂÂÂÂÂÂ ret = regulator_enable(mmc->supply.vqmmc);
>>>>>>> +ÂÂÂÂÂÂÂ if (!(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>>>>>>
>>>>>> And this could be:
>>>>>>
>>>>>> ÂÂÂÂÂÂÂÂÂ if (enable_vqmmc)
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂ ret = regulator_enable(mmc->supply.vqmmc);
>>>>>> ÂÂÂÂÂÂÂÂÂ else
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂ ret = 0;
>>>>>> ÂÂÂ> However, you still need to ensure
>>>>>> regulator_disable(mmc->supply.vqmmc) is
>>>>>> only called if regulator_enable() was called.
>>>>> I missed this. Will cover it.
>>>>>
>>>>> Also I missed one more place where we are doing regulator_disable. During
>>>>> sdhci-msm unbinding, we would end up doing an extra regulator disable
>>>>> (thanks Evan for pointing it out) in sdhci_remove_host.
>>>>>
>>>>> To avoid the quirk( or having any flag), it would require copying the code
>>>>> of sdhci_start_signal_voltage_switch() and sdhci_remove_host() and
>>>>> creating
>>>>
>>>> You do not need to duplicate sdhci_remove_host(), just change it so that it
>>>> only disables what was enabled i.e.
>>>>
>>>> ÂÂÂÂÂif (host->vqmmc_enabled)
>>>> ÂÂÂÂÂÂÂÂ regulator_disable(mmc->supply.vqmmc);
>>>>
>>>
>>> Ok, so we will be adding a new flag "vqmmc_enabled" in sdhci_host, ryt ?
>>
>> Yes
>>
> 
> Ok.
> Any particular reason why we are avoiding quirk and instead adding a new flag ?

It moves more in the direction of letting drivers do what they want, rather
than trying to make making SDHCI do everything.

> 
>>> Just wanted to clarify
>>>
>>>>> 2 new functions in sdhci_msm layer which would do the exact same as above,
>>>>> with just the regulator parts removed.
>>>>>
>>>>> This looks messy (considering any future changes to the 2 sdhci API will
>>>>> need to be copied to their duplicate sdhci_msm API) and a bit overkill to
>>>>> avoid quirk. At the same time, I don't know how useful such a quirk
>>>>> would be
>>>>> to other platform drivers.
>>>>>
>>>>> Please let me know your view/suggestions.
>>>>
>>>> Let's try without the quirk.
>>>>
>>>>>>
>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂ ret = regulator_enable(mmc->supply.vqmmc);
>>>>>>> +ÂÂÂÂÂÂÂ else
>>>>>>> +ÂÂÂÂÂÂÂÂÂÂÂ ret = 0;
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂ if (!regulator_is_supported_voltage(mmc->supply.vqmmc,
>>>>>>> 1700000,
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 1950000))
>>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ host->caps1 &= ~(SDHCI_SUPPORT_SDR104 |
>>>>>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>>>>>> index 23966f8..3b0c97a 100644
>>>>>>> --- a/drivers/mmc/host/sdhci.h
>>>>>>> +++ b/drivers/mmc/host/sdhci.h
>>>>>>> @@ -450,6 +450,8 @@ struct sdhci_host {
>>>>>>> ÂÂÂÂ * obtainable timeout.
>>>>>>> ÂÂÂÂ */
>>>>>>> ÂÂÂ #define SDHCI_QUIRK2_DISABLE_HW_TIMEOUTÂÂÂÂÂÂÂÂÂÂÂ (1<<17)
>>>>>>> +/* Regulator voltage changes are being done from platform layer */
>>>>>>> +#define SDHCI_QUIRK2_INTERNAL_PWR_CTLÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ (1<<18)
>>>>>>
>>>>>> So maybe the quirk is not needed.
>>>>>>
>>>>>>> ÂÂÂ ÂÂÂÂÂ int irq;ÂÂÂÂÂÂÂ /* Device IRQ */
>>>>>>> ÂÂÂÂÂÂÂ void __iomem *ioaddr;ÂÂÂ /* Mapped address */
>>>>>>>
>>>>>>
>>>>>
>>>>> Thanks for the review & suggestions!
>>>>> Vijay
>>>>>
>>>>
>>>
>>
>> -- 
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