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Message-ID: <78dfa5db-712b-bb0c-ad03-761371beef10@intel.com>
Date: Tue, 17 Jul 2018 10:30:35 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Vijay Viswanath <vviswana@...eaurora.org>, ulf.hansson@...aro.org,
robh+dt@...nel.org, mark.rutland@....com
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
shawn.lin@...k-chips.com, linux-arm-msm@...r.kernel.org,
georgi.djakov@...aro.org, devicetree@...r.kernel.org,
asutoshd@...eaurora.org, stummala@...eaurora.org,
venkatg@...eaurora.org, jeremymc@...hat.com,
bjorn.andersson@...aro.org, riteshh@...eaurora.org,
vbadigan@...eaurora.org, dianders@...gle.com,
sayalil@...eaurora.org, Evan Green <evgreen@...omium.org>
Subject: Re: [PATCH RFC 1/2] mmc: sdhci: Allow platform controlled voltage
switching
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@...eaurora.org>
>>> ---
>>> drivers/mmc/host/sdhci.c | 20 +++++++++++++++-----
>>> drivers/mmc/host/sdhci.h | 2 ++
>>> 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,
>>> void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
>>> unsigned short vdd)
>>> {
>>> - if (IS_ERR(host->mmc->supply.vmmc))
>>> + if (IS_ERR(host->mmc->supply.vmmc) ||
>>> + (host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>>
>> I think you should provide your own ->set_power() instead of this
>>
>
> will do
>
>>> sdhci_set_power_noreg(host, mode, vdd);
>>> else
>>> sdhci_set_power_reg(host, mode, vdd);
>>> @@ -2009,7 +2010,9 @@ int sdhci_start_signal_voltage_switch(struct
>>> mmc_host *mmc,
>>> ctrl &= ~SDHCI_CTRL_VDD_180;
>>> sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
>>> - if (!IS_ERR(mmc->supply.vqmmc)) {
>>> + if (!IS_ERR(mmc->supply.vqmmc) &&
>>> + !(host->quirks2 &
>>> + 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.
>
>>> ret = mmc_regulator_set_vqmmc(mmc, ios);
>>> if (ret) {
>>> 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,
>>> case MMC_SIGNAL_VOLTAGE_180:
>>> if (!(host->flags & SDHCI_SIGNALING_180))
>>> return -EINVAL;
>>> - if (!IS_ERR(mmc->supply.vqmmc)) {
>>> + if (!IS_ERR(mmc->supply.vqmmc) &&
>>> + !(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL)) {
>>> ret = mmc_regulator_set_vqmmc(mmc, ios);
>>> if (ret) {
>>> pr_warn("%s: Switching to 1.8V signalling voltage
>>> failed\n",
>>> @@ -3485,7 +3489,10 @@ int sdhci_setup_host(struct sdhci_host *host)
>>> * the host can take the appropriate action if regulators are not
>>> * available.
>>> */
>>> - ret = mmc_regulator_get_supply(mmc);
>>> + if (!(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>>
>> Since we expect mmc_regulator_get_supply() to have been called, this could
>> be:
>>
>> if (!mmc->supply.vmmc) {
>> ret = mmc_regulator_get_supply(mmc);
>> enable_vqmmc = true;
>> } else {
>> ret = 0;
>> }
>> >> + ret = mmc_regulator_get_supply(mmc);
>>> + else
>>> + ret = 0;
>>> if (ret)
>>> return ret;
>>> @@ -3736,7 +3743,10 @@ int sdhci_setup_host(struct sdhci_host *host)
>>> /* If vqmmc regulator and no 1.8V signalling, then there's no UHS */
>>> if (!IS_ERR(mmc->supply.vqmmc)) {
>>> - ret = regulator_enable(mmc->supply.vqmmc);
>>> + if (!(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>>
>> And this could be:
>>
>> if (enable_vqmmc)
>> ret = regulator_enable(mmc->supply.vqmmc);
>> else
>> ret = 0;
>> > 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.
if (host->vqmmc_enabled)
regulator_disable(mmc->supply.vqmmc);
> 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.
>>
>>> + ret = regulator_enable(mmc->supply.vqmmc);
>>> + else
>>> + ret = 0;
>>> if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000,
>>> 1950000))
>>> 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 {
>>> * obtainable timeout.
>>> */
>>> #define SDHCI_QUIRK2_DISABLE_HW_TIMEOUT (1<<17)
>>> +/* Regulator voltage changes are being done from platform layer */
>>> +#define SDHCI_QUIRK2_INTERNAL_PWR_CTL (1<<18)
>>
>> So maybe the quirk is not needed.
>>
>>> int irq; /* Device IRQ */
>>> void __iomem *ioaddr; /* Mapped address */
>>>
>>
>
> Thanks for the review & suggestions!
> Vijay
>
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