From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH RFC 1/2] mmc: sdhci: Allow platform controlled voltage switching Date: Tue, 17 Jul 2018 11:42:07 +0300 Message-ID: <6e8c713f-6569-25f3-dec5-f08001b3c6f3@intel.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Vijay Viswanath , 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 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 > 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 >>> >> >