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Date: Wed, 17 Jun 2020 16:16:00 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
Asutosh Das <asutoshd@...eaurora.org>,
Vijay Viswanath <vviswana@...eaurora.org>,
Andy Gross <agross@...nel.org>
Subject: Re: [PATCH V4 2/2] mmc: sdhci-msm: Use internal voltage control
On Wed, 17 Jun 2020 at 14:46, Veerabhadrarao Badiganti
<vbadigan@...eaurora.org> wrote:
>
> Thanks for comments Uffe.
>
> On 6/17/2020 3:04 PM, Ulf Hansson wrote:
> > On Tue, 16 Jun 2020 at 17:38, Veerabhadrarao Badiganti
> > <vbadigan@...eaurora.org> wrote:
> >> On qcom SD host controllers voltage switching be done after the HW
> >> is ready for it. The HW informs its readiness through power irq.
> >> The voltage switching should happen only then.
> >>
> >> Use the internal voltage switching and then control the voltage
> >> switching using power irq.
> >>
> >> IO-bus supply of eMMC would be kept always-on. So set the load
> >> for this supply to configure it in LPM when eMMC is suspend state
> >> and in HPM when eMMC is active.
> >>
> >> Co-developed-by: Asutosh Das <asutoshd@...eaurora.org>
> >> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> >> Co-developed-by: Vijay Viswanath <vviswana@...eaurora.org>
> >> Signed-off-by: Vijay Viswanath <vviswana@...eaurora.org>
> >> Co-developed-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
> >> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
> >> ---
> >> drivers/mmc/host/sdhci-msm.c | 208 +++++++++++++++++++++++++++++++++++++++++--
> >> 1 file changed, 199 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> >> index 15c42b059240..8297b2142748 100644
> >> --- a/drivers/mmc/host/sdhci-msm.c
> >> +++ b/drivers/mmc/host/sdhci-msm.c
> >> @@ -37,7 +37,9 @@
> >> #define CORE_PWRCTL_IO_LOW BIT(2)
> >> #define CORE_PWRCTL_IO_HIGH BIT(3)
> >> #define CORE_PWRCTL_BUS_SUCCESS BIT(0)
> >> +#define CORE_PWRCTL_BUS_FAIL BIT(1)
> >> #define CORE_PWRCTL_IO_SUCCESS BIT(2)
> >> +#define CORE_PWRCTL_IO_FAIL BIT(3)
> >> #define REQ_BUS_OFF BIT(0)
> >> #define REQ_BUS_ON BIT(1)
> >> #define REQ_IO_LOW BIT(2)
> >> @@ -127,6 +129,9 @@
> >> /* Timeout value to avoid infinite waiting for pwr_irq */
> >> #define MSM_PWR_IRQ_TIMEOUT_MS 5000
> >>
> >> +/* Max load for eMMC Vdd-io supply */
> >> +#define MMC_VQMMC_MAX_LOAD_UA 325000
> >> +
> >> #define msm_host_readl(msm_host, host, offset) \
> >> msm_host->var_ops->msm_readl_relaxed(host, offset)
> >>
> >> @@ -278,6 +283,7 @@ struct sdhci_msm_host {
> >> bool uses_tassadar_dll;
> >> u32 dll_config;
> >> u32 ddr_config;
> >> + bool vqmmc_enabled;
> >> };
> >>
> >> static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host)
> >> @@ -1346,6 +1352,88 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
> >> sdhci_msm_hs400(host, &mmc->ios);
> >> }
> >>
> >> +static int sdhci_msm_set_vmmc(struct mmc_host *mmc)
> >> +{
> >> + if (IS_ERR(mmc->supply.vmmc))
> >> + return 0;
> >> +
> >> + return mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, mmc->ios.vdd);
> >> +}
> >> +
> >> +static int msm_toggle_vqmmc(struct sdhci_msm_host *msm_host,
> >> + struct mmc_host *mmc, bool level)
> >> +{
> >> + int ret;
> >> + struct mmc_ios ios;
> >> +
> >> + if (msm_host->vqmmc_enabled == level)
> >> + return 0;
> >> +
> >> + if (level) {
> >> + /* Set the IO voltage regulator to default voltage level */
> >> + if (msm_host->caps_0 & CORE_3_0V_SUPPORT)
> >> + ios.signal_voltage = MMC_SIGNAL_VOLTAGE_330;
> >> + else if (msm_host->caps_0 & CORE_1_8V_SUPPORT)
> >> + ios.signal_voltage = MMC_SIGNAL_VOLTAGE_180;
> >> +
> >> + if (msm_host->caps_0 & CORE_VOLT_SUPPORT) {
> >> + ret = mmc_regulator_set_vqmmc(mmc, &ios);
> >> + if (ret < 0) {
> >> + dev_err(mmc_dev(mmc), "%s: vqmmc set volgate failed: %d\n",
> >> + mmc_hostname(mmc), ret);
> >> + goto out;
> >> + }
> >> + }
> >> + ret = regulator_enable(mmc->supply.vqmmc);
> >> + } else {
> >> + ret = regulator_disable(mmc->supply.vqmmc);
> >> + }
> >> +
> >> + if (ret)
> >> + dev_err(mmc_dev(mmc), "%s: vqmm %sable failed: %d\n",
> >> + mmc_hostname(mmc), level ? "en":"dis", ret);
> >> + else
> >> + msm_host->vqmmc_enabled = level;
> >> +out:
> >> + return ret;
> >> +}
> >> +
> >> +static int msm_config_vqmmc_mode(struct sdhci_msm_host *msm_host,
> >> + struct mmc_host *mmc, bool hpm)
> >> +{
> >> + int load, ret;
> >> +
> >> + load = hpm ? MMC_VQMMC_MAX_LOAD_UA : 0;
> >> + ret = regulator_set_load(mmc->supply.vqmmc, load);
> >> + if (ret)
> >> + dev_err(mmc_dev(mmc), "%s: vqmmc set load failed: %d\n",
> >> + mmc_hostname(mmc), ret);
> >> + return ret;
> >> +}
> >> +
> >> +static int sdhci_msm_set_vqmmc(struct sdhci_msm_host *msm_host,
> >> + struct mmc_host *mmc, bool level)
> >> +{
> >> + int ret;
> >> + bool always_on;
> >> +
> >> + if (IS_ERR(mmc->supply.vqmmc) ||
> > White space.
> >
> >> + (mmc->ios.power_mode == MMC_POWER_UNDEFINED))
> >> + return 0;
> >> + /*
> >> + * For eMMC don't turn off Vqmmc, Instead just configure it in LPM
> >> + * and HPM modes by setting the right amonut of load.
> > /s/right amonut of load/corresponding load
> >
> >> + */
> >> + always_on = mmc->card && mmc_card_mmc(mmc->card);
> >> +
> >> + if (always_on)
> >> + ret = msm_config_vqmmc_mode(msm_host, mmc, level);
> >> + else
> >> + ret = msm_toggle_vqmmc(msm_host, mmc, level);
> > I am worried that this isn't really doing what you think it does.
> > always_on may not always be set for an eMMC.
> >
> > This is because the mmc->card doesn't get assigned until the
> > initialization of the eMMC has been completed. In other words, way
> > after VCC and VCCQ have been turned on and changed voltage levels.
> For the very first time, i have to enable the vqmmc.
> And second time on-wards I have to set load instead of turning vqmmc off
> / on.
>
> This condition helps me in doing exactly the same.
>
> This gets invoked first time when mmc_power_up() is called.
> Yes, by that time card won't be initialized. So this check fails and
> allows to turn on the regulator instead of setting load.
>
> After that, this gets invoked only next time mmc_power_up/off() is called
> which is during mmc_suspend/resume.
I see.
That assumes the initialization always works at the first attempt, so
no re-try or power cycle gets done in some error/reset path.
>
> By this time card is initialized, it allows to set load.
Okay, I get it. Thanks for clarifying.
Perhaps you can add a small comment about this in the code, so we
don't forget the reasons why the code looks like this.
>
>
> > Moreover, mmc_card_mmc() is also about legacy MMC cards, not solely for eMMCs.
>
> Okay. But on qcom platform, we have support for only eMMC/SD/SDIO.
> So this mmc_card_mmc() meets my requirements!!! Allows only eMMC not SD
> & SDIO.
Well, eMMC is fairly similar to MMC, from a basic functionality point
of view. So, I am quite sure you can get it to work with your
controller, even if it's not officially supported.
>
> > If you want special treatment of an eMMC, I think it's better to use
> > the DT bindings Documentation/devicetree/bindings/mmc/mmc-card.txt. If
> > you have such a subnode, that indicates that there is an eMMC card
> > attached.
That said, if you don't like the pure DT based solution, as I
suggested above - at least extend mmc_card_mmc() with checking the
MMC_CAP_NONREMOVABLE flag.
[...]
Kind regards
Uffe
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