[PATCH] mmc: host: sdhci-esdhc-imx: save tuning value for the card which keep power in suspend
Luke Wang
ziniu.wang_1 at nxp.com
Thu Mar 27 19:59:06 PDT 2025
> -----Original Message-----
> From: Frank Li <frank.li at nxp.com>
> Sent: Friday, March 28, 2025 1:07 AM
> To: Luke Wang <ziniu.wang_1 at nxp.com>
> Cc: adrian.hunter at intel.com; ulf.hansson at linaro.org; Bough Chen
> <haibo.chen at nxp.com>; shawnguo at kernel.org; s.hauer at pengutronix.de;
> kernel at pengutronix.de; festevam at gmail.com; imx at lists.linux.dev; linux-
> mmc at vger.kernel.org; dl-S32 <S32 at nxp.com>; linux-arm-
> kernel at lists.infradead.org; linux-kernel at vger.kernel.org
> Subject: Re: [PATCH] mmc: host: sdhci-esdhc-imx: save tuning value for the
> card which keep power in suspend
>
> On Tue, Mar 25, 2025 at 05:43:30PM +0800, ziniu.wang_1 at nxp.com wrote:
> > From: Luke Wang <ziniu.wang_1 at nxp.com>
> >
> > For some SoCs like imx6ul(l/z) and imx7d, during system PM, usdhc will
> > totally power off, so the internal tuning status will lost. Here add
> > save/restore the tuning value for any command after system resume back
> > when re-tuning hold.
> >
> > The tipical case is for the SDIO WIFI which contain flag
> MMC_PM_KEEP_POWER,
>
> tipical? most like typo typical, you can run
> ./scripts/checkpatch.pl -g HEAD --strict --codespell
>
Yes, it's a typo. Will check the spell next time.
>
> > it means this device will keep power during system PM. To save power, WIFI
> > will switch to 1 bit mode, and switch back to 4 bit mode when resume back.
> > According to spec, tuning command do not support in 1 bit mode. So when
> > send cmd52 to switch back to 4 bit mode, need to hold re-tuning. But this
> > cmd52 still need a correct sample point, otherwise will meet command CRC
> > error, so need to keep the previous tuning value.
>
> AI tuned commit message as reference.
>
> "For SoCs like i.MX6UL(L/Z) and i.MX7D, USDHC powers off completely during
> system power management (PM), causing the internal tuning status to be lost.
> To address this, save and restore the tuning value for any command issued
> after system resume when re-tuning is held.
>
> A typical case involves SDIO WiFi devices with the MMC_PM_KEEP_POWER
> flag,
> which retain power during system PM. To conserve power, WiFi switches to
> 1-bit mode and restores 4-bit mode upon resume. As per the specification,
> tuning commands are not supported in 1-bit mode. When sending CMD52 to
> restore 4-bit mode, re-tuning must be held. However, CMD52 still requires
> a correct sample point to avoid CRC errors, necessitating preservation of
> the previous tuning value."
>
Will update the commit message.
> >
> > Signed-off-by: Luke Wang <ziniu.wang_1 at nxp.com>
> > ---
> > drivers/mmc/host/sdhci-esdhc-imx.c | 90
> +++++++++++++++++++++++++++++-
> > 1 file changed, 88 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-
> esdhc-imx.c
> > index ff78a7c6a04c..d3ac5f38a9eb 100644
> > --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> > +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> > @@ -81,6 +81,9 @@
> > #define ESDHC_TUNE_CTRL_STEP 1
> > #define ESDHC_TUNE_CTRL_MIN 0
> > #define ESDHC_TUNE_CTRL_MAX ((1 << 7) - 1)
> > +#define ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_MASK
> 0x7f000000
>
> Use GEN_MASK
OK, looks better
>
> > +#define ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_SHIFT 24
> > +#define ESDHC_TUNE_CTRL_STATUS_DLY_CELL_SET_PRE_SHIFT 8
> >
> > /* strobe dll register */
> > #define ESDHC_STROBE_DLL_CTRL 0x70
> > @@ -235,6 +238,7 @@ struct esdhc_platform_data {
> > unsigned int tuning_step; /* The delay cell steps in tuning
> procedure */
> > unsigned int tuning_start_tap; /* The start delay cell point in tuning
> procedure */
> > unsigned int strobe_dll_delay_target; /* The delay cell for strobe
> pad (read clock) */
> > + unsigned int saved_tuning_delay_cell; /* save the value of tuning
> delay cell */
> > };
> >
> > struct esdhc_soc_data {
> > @@ -1057,7 +1061,7 @@ static void esdhc_reset_tuning(struct sdhci_host
> *host)
> > {
> > struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
> > - u32 ctrl;
> > + u32 ctrl, tuning_ctrl;
> > int ret;
> >
> > /* Reset the tuning circuit */
> > @@ -1071,6 +1075,16 @@ static void esdhc_reset_tuning(struct
> sdhci_host *host)
> > writel(0, host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
> > } else if (imx_data->socdata->flags &
> ESDHC_FLAG_STD_TUNING) {
> > writel(ctrl, host->ioaddr + ESDHC_MIX_CTRL);
> > + /*
> > + * enable the std tuning just in case it cleared in
> > + * sdhc_esdhc_tuning_restore.
> > + */
> > + tuning_ctrl = readl(host->ioaddr +
> ESDHC_TUNING_CTRL);
> > + if (!(tuning_ctrl & ESDHC_STD_TUNING_EN)) {
> > + tuning_ctrl |= ESDHC_STD_TUNING_EN;
> > + writel(tuning_ctrl, host->ioaddr +
> ESDHC_TUNING_CTRL);
> > + }
> > +
> > ctrl = readl(host->ioaddr +
> SDHCI_AUTO_CMD_STATUS);
> > ctrl &= ~ESDHC_MIX_CTRL_SMPCLK_SEL;
> > ctrl &= ~ESDHC_MIX_CTRL_EXE_TUNE;
> > @@ -1149,7 +1163,8 @@ static void esdhc_prepare_tuning(struct
> sdhci_host *host, u32 val)
> > reg |= ESDHC_MIX_CTRL_EXE_TUNE |
> ESDHC_MIX_CTRL_SMPCLK_SEL |
> > ESDHC_MIX_CTRL_FBCLK_SEL;
> > writel(reg, host->ioaddr + ESDHC_MIX_CTRL);
> > - writel(val << 8, host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
> > + writel(val << ESDHC_TUNE_CTRL_STATUS_DLY_CELL_SET_PRE_SHIFT,
> > + host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
>
> FIELD_PREP ?
OK
>
> > dev_dbg(mmc_dev(host->mmc),
> > "tuning with delay 0x%x ESDHC_TUNE_CTRL_STATUS
> 0x%x\n",
> > val, readl(host->ioaddr +
> ESDHC_TUNE_CTRL_STATUS));
> > @@ -1569,6 +1584,58 @@ static void sdhci_esdhc_imx_hwinit(struct
> sdhci_host *host)
> > }
> > }
> >
> > +static void sdhc_esdhc_tuning_save(struct sdhci_host *host)
> > +{
> > + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > + struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
> > + u32 reg;
> > +
> > + /*
> > + * SD/eMMC do not need this tuning save because it will re-init
> > + * after system resume back.
> > + * Here save the tuning delay value for SDIO device since it may
> > + * keep power during system PM. And for usdhc, only SDR50 and
> > + * SDR104 mode for SDIO devide need to do tuning, and need to
> > + * save/restore.
> > + */
> > + if ((host->timing == MMC_TIMING_UHS_SDR50) ||
> > + (host->timing == MMC_TIMING_UHS_SDR104)) {
> > + reg = readl(host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
> > + reg = (reg &
> ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_MASK) >>
> > +
> ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_SHIFT;
>
> FILED_GET?
OK
Thanks Frank
Luke
>
> Frank
>
> > + imx_data->boarddata.saved_tuning_delay_cell = reg;
> > + }
> > +}
> > +
> > +static void sdhc_esdhc_tuning_restore(struct sdhci_host *host)
> > +{
> > + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > + struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
> > + u32 reg;
> > +
> > + if ((host->timing == MMC_TIMING_UHS_SDR50) ||
> > + (host->timing == MMC_TIMING_UHS_SDR104)) {
> > + /*
> > + * restore the tuning delay value actually is a
> > + * manual tuning method, so clear the standard
> > + * tuning enable bit here. Will set back this
> > + * ESDHC_STD_TUNING_EN in esdhc_reset_tuning()
> > + * when trigger re-tuning.
> > + */
> > + reg = readl(host->ioaddr + ESDHC_TUNING_CTRL);
> > + reg &= ~ESDHC_STD_TUNING_EN;
> > + writel(reg, host->ioaddr + ESDHC_TUNING_CTRL);
> > +
> > + reg = readl(host->ioaddr + ESDHC_MIX_CTRL);
> > + reg |= ESDHC_MIX_CTRL_SMPCLK_SEL |
> ESDHC_MIX_CTRL_FBCLK_SEL;
> > + writel(reg, host->ioaddr + ESDHC_MIX_CTRL);
> > +
> > + writel(imx_data->boarddata.saved_tuning_delay_cell <<
> > +
> ESDHC_TUNE_CTRL_STATUS_DLY_CELL_SET_PRE_SHIFT,
> > + host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
> > + }
> > +}
> > +
> > static void esdhc_cqe_enable(struct mmc_host *mmc)
> > {
> > struct sdhci_host *host = mmc_priv(mmc);
> > @@ -1900,6 +1967,15 @@ static int sdhci_esdhc_suspend(struct device
> *dev)
> > if (host->tuning_mode != SDHCI_TUNING_MODE_3)
> > mmc_retune_needed(host->mmc);
> >
> > + /*
> > + * For the device need to keep power during system PM, need
> > + * to save the tuning delay value just in case the usdhc
> > + * lost power during system PM.
> > + */
> > + if (mmc_card_keep_power(host->mmc) &&
> > + (esdhc_is_usdhc(imx_data)))
> > + sdhc_esdhc_tuning_save(host);
> > +
> > ret = sdhci_suspend_host(host);
> > if (ret)
> > return ret;
> > @@ -1916,6 +1992,8 @@ static int sdhci_esdhc_suspend(struct device
> *dev)
> > static int sdhci_esdhc_resume(struct device *dev)
> > {
> > struct sdhci_host *host = dev_get_drvdata(dev);
> > + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > + struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
> > int ret;
> >
> > ret = pinctrl_pm_select_default_state(dev);
> > @@ -1929,6 +2007,14 @@ static int sdhci_esdhc_resume(struct device
> *dev)
> > if (ret)
> > return ret;
> >
> > + /*
> > + * restore the saved tuning delay value for the device which keep
> > + * power during system PM.
> > + */
> > + if (mmc_card_keep_power(host->mmc) &&
> > + (esdhc_is_usdhc(imx_data)))
> > + sdhc_esdhc_tuning_restore(host);
> > +
> > if (host->mmc->caps2 & MMC_CAP2_CQE)
> > ret = cqhci_resume(host->mmc);
> >
> > --
> > 2.34.1
> >
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