Re: [PATCH] mmc: rtsx_pci_sdmmc: simplify voltage switch handling after card_busy()

[Ulf Hansson]

On Fri, 30 Jan 2026 at 04:05, <ricky_wu@xxxxxxxxxxx> wrote:
>
> From: Ricky Wu <ricky_wu@xxxxxxxxxxx>
>
> Now that the Realtek PCIe SDMMC host implements the card_busy() callback,
> the MMC core performs the required DAT[3:0] validation during the signal
> voltage switch sequence.
>
> As a result, the driver-side voltage stabilization helpers
> sd_wait_voltage_stable_1() and sd_wait_voltage_stable_2() become redundant.
> These helpers duplicate DAT line checks that are now handled centrally by
> the MMC core via card_busy().
>
> Remove the two stabilization helpers and simplify sdmmc_switch_voltage()
> accordingly, keeping only the minimal clock control needed around the
> voltage switch.
>
> No functional changes and intended.
>
> Signed-off-by: Ricky Wu <ricky_wu@xxxxxxxxxxx>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/rtsx_pci_sdmmc.c | 88 +++----------------------------
>  1 file changed, 6 insertions(+), 82 deletions(-)
>
> diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
> index 4db3328f46df..8dfbc62f165b 100644
> --- a/drivers/mmc/host/rtsx_pci_sdmmc.c
> +++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
> @@ -1181,79 +1181,6 @@ static int sdmmc_get_cd(struct mmc_host *mmc)
>         return cd;
>  }
>
> -static int sd_wait_voltage_stable_1(struct realtek_pci_sdmmc *host)
> -{
> -       struct rtsx_pcr *pcr = host->pcr;
> -       int err;
> -       u8 stat;
> -
> -       /* Reference to Signal Voltage Switch Sequence in SD spec.
> -        * Wait for a period of time so that the card can drive SD_CMD and
> -        * SD_DAT[3:0] to low after sending back CMD11 response.
> -        */
> -       mdelay(1);
> -
> -       /* SD_CMD, SD_DAT[3:0] should be driven to low by card;
> -        * If either one of SD_CMD,SD_DAT[3:0] is not low,
> -        * abort the voltage switch sequence;
> -        */
> -       err = rtsx_pci_read_register(pcr, SD_BUS_STAT, &stat);
> -       if (err < 0)
> -               return err;
> -
> -       if (stat & (SD_CMD_STATUS | SD_DAT3_STATUS | SD_DAT2_STATUS |
> -                               SD_DAT1_STATUS | SD_DAT0_STATUS))
> -               return -EINVAL;
> -
> -       /* Stop toggle SD clock */
> -       err = rtsx_pci_write_register(pcr, SD_BUS_STAT,
> -                       0xFF, SD_CLK_FORCE_STOP);
> -       if (err < 0)
> -               return err;
> -
> -       return 0;
> -}
> -
> -static int sd_wait_voltage_stable_2(struct realtek_pci_sdmmc *host)
> -{
> -       struct rtsx_pcr *pcr = host->pcr;
> -       int err;
> -       u8 stat, mask, val;
> -
> -       /* Wait 1.8V output of voltage regulator in card stable */
> -       msleep(50);
> -
> -       /* Toggle SD clock again */
> -       err = rtsx_pci_write_register(pcr, SD_BUS_STAT, 0xFF, SD_CLK_TOGGLE_EN);
> -       if (err < 0)
> -               return err;
> -
> -       /* Wait for a period of time so that the card can drive
> -        * SD_DAT[3:0] to high at 1.8V
> -        */
> -       msleep(20);
> -
> -       /* SD_CMD, SD_DAT[3:0] should be pulled high by host */
> -       err = rtsx_pci_read_register(pcr, SD_BUS_STAT, &stat);
> -       if (err < 0)
> -               return err;
> -
> -       mask = SD_CMD_STATUS | SD_DAT3_STATUS | SD_DAT2_STATUS |
> -               SD_DAT1_STATUS | SD_DAT0_STATUS;
> -       val = SD_CMD_STATUS | SD_DAT3_STATUS | SD_DAT2_STATUS |
> -               SD_DAT1_STATUS | SD_DAT0_STATUS;
> -       if ((stat & mask) != val) {
> -               dev_dbg(sdmmc_dev(host),
> -                       "%s: SD_BUS_STAT = 0x%x\n", __func__, stat);
> -               rtsx_pci_write_register(pcr, SD_BUS_STAT,
> -                               SD_CLK_TOGGLE_EN | SD_CLK_FORCE_STOP, 0);
> -               rtsx_pci_write_register(pcr, CARD_CLK_EN, 0xFF, 0);
> -               return -EINVAL;
> -       }
> -
> -       return 0;
> -}
> -
>  static int sdmmc_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios)
>  {
>         struct realtek_pci_sdmmc *host = mmc_priv(mmc);
> @@ -1281,7 +1208,9 @@ static int sdmmc_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios)
>                 voltage = OUTPUT_1V8;
>
>         if (voltage == OUTPUT_1V8) {
> -               err = sd_wait_voltage_stable_1(host);
> +               /* Stop toggle SD clock */
> +               err = rtsx_pci_write_register(pcr, SD_BUS_STAT,
> +                               0xFF, SD_CLK_FORCE_STOP);
>                 if (err < 0)
>                         goto out;
>         }
> @@ -1290,16 +1219,11 @@ static int sdmmc_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios)
>         if (err < 0)
>                 goto out;
>
> -       if (voltage == OUTPUT_1V8) {
> -               err = sd_wait_voltage_stable_2(host);
> -               if (err < 0)
> -                       goto out;
> -       }
> -
>  out:
>         /* Stop toggle SD clock in idle */
> -       err = rtsx_pci_write_register(pcr, SD_BUS_STAT,
> -                       SD_CLK_TOGGLE_EN | SD_CLK_FORCE_STOP, 0);
> +       if (err < 0)
> +               rtsx_pci_write_register(pcr, SD_BUS_STAT,
> +                               SD_CLK_TOGGLE_EN | SD_CLK_FORCE_STOP, 0);
>
>         mutex_unlock(&pcr->pcr_mutex);
>
> --
> 2.25.1
>