From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vijay Viswanath Subject: Re: [PATCH RFC 1/2] mmc: sdhci: Allow platform controlled voltage switching Date: Tue, 17 Jul 2018 15:52:00 +0530 Message-ID: <63819f9c-e4a6-1a71-5cca-3efcfa843206@codeaurora.org> References: <1529583826-42020-1-git-send-email-vviswana@codeaurora.org> <1529583826-42020-2-git-send-email-vviswana@codeaurora.org> <53c6d61f-47f5-2e4e-8280-6f76f707799e@intel.com> <0d9b1934-d80d-a726-8094-688c97474afa@codeaurora.org> <78dfa5db-712b-bb0c-ad03-761371beef10@intel.com> <6e8c713f-6569-25f3-dec5-f08001b3c6f3@intel.com> <8c4fb768-3d4f-da45-3115-30bc5c1058a6@codeaurora.org> <82109d4a-6e3c-eb80-6843-75bf7c89c113@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <82109d4a-6e3c-eb80-6843-75bf7c89c113@intel.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Adrian Hunter , ulf.hansson@linaro.org, robh+dt@kernel.org, mark.rutland@arm.com Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, shawn.lin@rock-chips.com, linux-arm-msm@vger.kernel.org, georgi.djakov@linaro.org, devicetree@vger.kernel.org, asutoshd@codeaurora.org, stummala@codeaurora.org, venkatg@codeaurora.org, jeremymc@redhat.com, bjorn.andersson@linaro.org, riteshh@codeaurora.org, vbadigan@codeaurora.org, dianders@google.com, sayalil@codeaurora.org, Evan Green List-Id: devicetree@vger.kernel.org On 7/17/2018 3:24 PM, Adrian Hunter wrote: > 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 >>>>>>>> --- >>>>>>>>     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); >>>>> >>>> >>>> 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. > ok will incorporate the changes in next version. >> >>>> 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. >>>>> >>>>>>> >>>>>>>> +            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 >>>>>> >>>>> >>>> >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at  http://vger.kernel.org/majordomo-info.html >>> >> > Thanks, Vijay