Messages in this thread Patch in this message | | | From | Vijay Viswanath <> | Subject | Re: [PATCH RFC 1/2] mmc: sdhci: Allow platform controlled voltage switching | Date | Tue, 17 Jul 2018 10:44:49 +0530 |
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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 <vviswana@codeaurora.org> >> --- >> 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 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. > >> + 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
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