RE: [PATCH v18 09/12] mmc: renesas_sdhi: Save and restore IOVS across suspend/resume

Hi Wolfram,

> -----Original Message-----
> From: Biju <[email protected]>
> Sent: 22 June 2026 16:56
> Subject: [PATCH v18 09/12] mmc: renesas_sdhi: Save and restore IOVS across suspend/resume
> 
> From: Biju Das <[email protected]>
> 
> The SD_STATUS register, specifically the IOVS (I/O Voltage Switch) bit, is not automatically restored
> after a suspend/resume cycle, causing the regulator to report an incorrect voltage on resume.
> 
> Fix this by caching the CTL_SD_STATUS register value in the renesas_sdhi private struct at suspend time
> and writing it back during resume. The save/restore is only performed when a regulator device (rdev) is
> present, as the IOVS bit is only relevant in that context.
> 
> Signed-off-by: Biju Das <[email protected]>
> ---
> v17->v18:
>  * No change.
> v1->v17:
>  * No change.
> ---
>  drivers/mmc/host/renesas_sdhi.h      | 1 +
>  drivers/mmc/host/renesas_sdhi_core.c | 6 ++++++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/mmc/host/renesas_sdhi.h b/drivers/mmc/host/renesas_sdhi.h index
> 9ac5cb25ee98..9d5e591ef2f5 100644
> --- a/drivers/mmc/host/renesas_sdhi.h
> +++ b/drivers/mmc/host/renesas_sdhi.h
> @@ -106,6 +106,7 @@ struct renesas_sdhi {
>  	struct regulator_dev *rdev;
> 
>  	unsigned int divider;
> +	u32 cache_sd_status;
>  };
> 
>  #define host_to_priv(host) \
> diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
> index 8e14ce3ca7ba..f77985d305c0 100644
> --- a/drivers/mmc/host/renesas_sdhi_core.c
> +++ b/drivers/mmc/host/renesas_sdhi_core.c
> @@ -1391,6 +1391,9 @@ int renesas_sdhi_suspend(struct device *dev)
>  	};
>  	int ret;
> 
> +	if (priv->rdev)
> +		priv->cache_sd_status = sd_ctrl_read32(host, CTL_SD_STATUS);
> +
>  	ret = pm_runtime_force_suspend(dev);
>  	if (ret)
>  		return ret;
> @@ -1422,6 +1425,9 @@ int renesas_sdhi_resume(struct device *dev)
>  	if (ret)
>  		reset_control_bulk_assert(ARRAY_SIZE(resets), resets);
> 
> +	if (priv->rdev)
> +		sd_ctrl_write32(host, CTL_SD_STATUS, priv->cache_sd_status);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(renesas_sdhi_resume);
> --
> 2.43.0

[1] https://sashiko.dev/#/patchset/20260622155610.184271-1-biju.das.jz%40bp.renesas.com

OK will add the scoped pm calls before accessing the register.

+	PM_RUNTIME_ACQUIRE_IF_ENABLED(lvds->dev, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);

Cheers,
Biju