From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH V1 1/3] mmc: sdhci: Allow platform controlled voltage switching Date: Wed, 25 Jul 2018 15:37:29 +0300 Message-ID: References: <1532083566-43215-1-git-send-email-vviswana@codeaurora.org> <1532083566-43215-2-git-send-email-vviswana@codeaurora.org> <33e12e51-4b96-032f-845f-7910d654018c@intel.com> <42ee57f7-8a99-b815-12db-2727ed67872b@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <42ee57f7-8a99-b815-12db-2727ed67872b@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, evgreen@chromium.org, dianders@google.com, sayalil@codeaurora.org, rampraka@codeaurora.org List-Id: devicetree@vger.kernel.org On 25/07/18 15:23, Vijay Viswanath wrote: > Hi Adrian, > > > On 7/25/2018 5:23 PM, Adrian Hunter wrote: >> On 20/07/18 13:46, 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. >>> >>> During setup/cleanup of host, check whether regulator enable/disable >>> was already done by platform driver. >>> >>> Signed-off-by: Vijay Viswanath >>> --- >>>   drivers/mmc/host/sdhci.c | 21 ++++++++++++++++----- >>>   1 file changed, 16 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >>> index 1c828e0..494a1e2 100644 >>> --- a/drivers/mmc/host/sdhci.c >>> +++ b/drivers/mmc/host/sdhci.c >>> @@ -3472,6 +3472,7 @@ int sdhci_setup_host(struct sdhci_host *host) >>>       unsigned int override_timeout_clk; >>>       u32 max_clk; >>>       int ret; >>> +    bool enable_vqmmc = false; >>>         WARN_ON(host == NULL); >>>       if (host == NULL) >>> @@ -3485,7 +3486,12 @@ 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 (!mmc->supply.vmmc) { >>> +        ret = mmc_regulator_get_supply(mmc); >>> +        enable_vqmmc  = true; >>> +    } else { >>> +        ret = 0; >>> +    } >>>       if (ret) >>>           return ret; >> >> Why not >> >>     if (!mmc->supply.vmmc) { >>         ret = mmc_regulator_get_supply(mmc); >>           if (ret) >>                return ret; >>         enable_vqmmc  = true; >>     } >> > > looks neater. Will do. > >>>   @@ -3736,7 +3742,10 @@ 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 (enable_vqmmc) >>> +            ret = regulator_enable(mmc->supply.vqmmc); >> >> Please introduce host->vqmmc_enabled = !ret; >> > > Any reason to introduce vqmmc_enabled variable in sdhci_host structure ? We > can get around with a local variable and using regulator_is_enabled API. regulator_enable() uses reference counting, so we have to use regulator_disable() exactly the same number of times that we use regulator_enable(). > >>> +        else >>> +            ret = 0; >>>           if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000, >>>                               1950000)) >>>               host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | >>> @@ -3984,7 +3993,7 @@ int sdhci_setup_host(struct sdhci_host *host) >>>       return 0; >>>     unreg: >>> -    if (!IS_ERR(mmc->supply.vqmmc)) >>> +    if (!IS_ERR(mmc->supply.vqmmc) && enable_vqmmc) >> >> And just make this >> >>     if (host->vqmmc_enabled) >> >>>           regulator_disable(mmc->supply.vqmmc); >>>   undma: >>>       if (host->align_buffer) >>> @@ -4002,7 +4011,8 @@ void sdhci_cleanup_host(struct sdhci_host *host) >>>   { >>>       struct mmc_host *mmc = host->mmc; >>>   -    if (!IS_ERR(mmc->supply.vqmmc)) >>> +    if (!IS_ERR(mmc->supply.vqmmc) && >>> +            (regulator_is_enabled(mmc->supply.vqmmc) > 0)) >> >>     if (host->vqmmc_enabled) >> >>>           regulator_disable(mmc->supply.vqmmc); >>>         if (host->align_buffer) >>> @@ -4135,7 +4145,8 @@ void sdhci_remove_host(struct sdhci_host *host, int >>> dead) >>>         tasklet_kill(&host->finish_tasklet); >>>   -    if (!IS_ERR(mmc->supply.vqmmc)) >>> +    if (!IS_ERR(mmc->supply.vqmmc) && >>> +            (regulator_is_enabled(mmc->supply.vqmmc) > 0)) >> >>     if (host->vqmmc_enabled) >> >>>           regulator_disable(mmc->supply.vqmmc); >>>         if (host->align_buffer) >>> >> >> -- >> 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 >