Re: [PATCH] mmc: cv1800b_sdhci: configure SDHCI PHY

[Yao Zi <me@ziyao.cc>]

On Mon, Sep 07, 2026 at 04:54:35PM +0200, Andrei Lalaev wrote:
> Some samples of the Milk-V Duo and Duo 256M have issues with SD card
> communication. As a result, the SD card is not detected, or the correct
> mode is not selected.
> 
> Configure SDHCI PHY in the same way as in downstream, to ensure
> that the PHY is initialized properly.
> 
> Fixes: eb36f28ff721 ("mmc: cv1800b: Add sdhci driver support for cv1800b SoC")
> Signed-off-by: Andrei Lalaev <andrey.lalaev@gmail.com>
> Link: https://lore.kernel.org/u-boot/20260822091510.3253162-1-andrey.lalaev@gmail.com/
> ---
>  drivers/mmc/cv1800b_sdhci.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/mmc/cv1800b_sdhci.c b/drivers/mmc/cv1800b_sdhci.c
> index b756649f90f3..5c129682daba 100644
> --- a/drivers/mmc/cv1800b_sdhci.c
> +++ b/drivers/mmc/cv1800b_sdhci.c
> @@ -8,11 +8,17 @@
>  #include <sdhci.h>
>  #include <linux/delay.h>
>  
> +#define CV18XX_SDHCI_MSHC_CTRL  0x200
> +#define CV18XX_SDHCI_PHY_CONFIG 0x24c
>  #define SDHCI_PHY_TX_RX_DLY  0x240
>  #define MMC_MAX_CLOCK        375000000
>  #define TUNE_MAX_PHCODE      128
>  
>  #define PHY_TX_SRC_INVERT  BIT(8)
> +#define PHY_RX_SRC_INVERT  BIT(24)
> +
> +#define CV18XX_LATANCY_1T BIT(1)
> +#define CV18XX_PHY_TX_BPS BIT(0)
>  
>  struct cv1800b_sdhci_plat {
>  	struct mmc_config cfg;
> @@ -64,10 +70,29 @@ static int cv1800b_execute_tuning(struct mmc *mmc, u8 opcode)
>  }
>  #endif
>  
> +static int cv1800b_deferred_probe(struct sdhci_host *host)
> +{
> +	u32 val;
> +
> +	val = sdhci_readl(host, CV18XX_SDHCI_MSHC_CTRL);
> +	val |= CV18XX_LATANCY_1T;
> +	sdhci_writel(host, val, CV18XX_SDHCI_MSHC_CTRL);
> +
> +	val = sdhci_readl(host, CV18XX_SDHCI_PHY_CONFIG);
> +	val |= CV18XX_PHY_TX_BPS;
> +	sdhci_writel(host, val, CV18XX_SDHCI_PHY_CONFIG);
> +
> +	val = PHY_TX_SRC_INVERT | PHY_RX_SRC_INVERT;
> +	sdhci_writel(host, val, SDHCI_PHY_TX_RX_DLY);
> +
> +	return 0;
> +}
> +
>  const struct sdhci_ops cv1800b_sdhci_sd_ops = {
>  #if CONFIG_IS_ENABLED(MMC_SUPPORTS_TUNING)
>  	.platform_execute_tuning = cv1800b_execute_tuning,
>  #endif
> +	.deferred_probe = cv1800b_deferred_probe,

Is there a reason to create a new function, instead of including the
logic somewhere already existing, for example, cv1800b_sdhci_reset()?
It seems to fit in cv1800b_sdhci_reset(), too, if it's for
initialization of the PHY.

Best regards,
Yao Zi