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 10:30:35 +0300 Message-ID: <78dfa5db-712b-bb0c-ad03-761371beef10@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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <0d9b1934-d80d-a726-8094-688c97474afa@codeaurora.org> 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 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); > 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 >