Re: [PATCH] mmc: core: sdio: hold retuning if sdio in 1-bit mode

[Adrian Hunter <adrian.hunter@intel.com>]

On 30/08/23 12:39, haibo.chen@nxp.com wrote:
> From: Haibo Chen <haibo.chen@nxp.com>
> 
> tuning only support in 4-bit mode or 8 bit mode, so in 1-bit mode,
> need to hold retuning.
> 
> Find this issue when use manual tuning method on imx93. When system
> resume back, SDIO WIFI try to switch back to 4 bit mode, first will
> trigger retuning, and all tuning command failed.
> 
> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>

UHS-I is also not meant for 1-bit mode, but I guess switching modes
in this case is also risky.

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

Fixes tag?

> ---
>  drivers/mmc/core/sdio.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
> index f64b9ac76a5c..5914516df2f7 100644
> --- a/drivers/mmc/core/sdio.c
> +++ b/drivers/mmc/core/sdio.c
> @@ -1089,8 +1089,14 @@ static int mmc_sdio_resume(struct mmc_host *host)
>  		}
>  		err = mmc_sdio_reinit_card(host);
>  	} else if (mmc_card_wake_sdio_irq(host)) {
> -		/* We may have switched to 1-bit mode during suspend */
> +		/*
> +		 * We may have switched to 1-bit mode during suspend,
> +		 * need to hold retuning, because tuning only supprt
> +		 * 4-bit mode or 8 bit mode.
> +		 */
> +		mmc_retune_hold_now(host);
>  		err = sdio_enable_4bit_bus(host->card);
> +		mmc_retune_release(host);
>  	}
>  
>  	if (err)