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 14:10:21 +0530 Message-ID: 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; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <78dfa5db-712b-bb0c-ad03-761371beef10@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 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 ? 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 >> >