[PATCH] mmc: fsl_esdhc: Fix 'Internal clock never stabilised.' error

[Jaehoon Chung]

On 4/30/22 03:27, Pali Rohár wrote:
> Only newer eSDHC controllers set PRSSTAT_SDSTB flag. So do not wait until
> flag PRSSTAT_SDSTB is set on old pre-2.2 controllers. Instead sleep for
> fixed amount of time like it was before commit 6f883e501b65 ("mmc:
> fsl_esdhc: Add emmc hs200 support").
> 
> This change fixes error 'Internal clock never stabilised.' which is printed
> on P2020 board at every access to SD card.
> 
> Fixes: 6f883e501b65 ("mmc: fsl_esdhc: Add emmc hs200 support")
> Signed-off-by: Pali Rohár <pali at kernel.org>

Reviewed-by: Jaehoon Chung <jh80.chung at samsung.com>

Just add minor question. 

> ---
>  drivers/mmc/fsl_esdhc.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
> index fdf2cc290e06..3b3587bd8d72 100644
> --- a/drivers/mmc/fsl_esdhc.c
> +++ b/drivers/mmc/fsl_esdhc.c
> @@ -503,6 +503,7 @@ static void set_sysctl(struct fsl_esdhc_priv *priv, struct mmc *mmc, uint clock)
>  	u32 time_out;
>  	u32 value;
>  	uint clk;
> +	u32 hostver;
>  
>  	if (clock < mmc->cfg->f_min)
>  		clock = mmc->cfg->f_min;
> @@ -543,6 +544,14 @@ static void set_sysctl(struct fsl_esdhc_priv *priv, struct mmc *mmc, uint clock)
>  
>  	esdhc_clrsetbits32(&regs->sysctl, SYSCTL_CLOCK_MASK, clk);
>  
> +	/* Only newer eSDHC controllers set PRSSTAT_SDSTB flag */
> +	hostver = esdhc_read32(&priv->esdhc_regs->hostver);
> +	if (HOSTVER_VENDOR(hostver) <= VENDOR_V_22) {
> +		udelay(10000);

Is there any reason to use 10000?

Best Regards,
Jaehoon Chung

> +		esdhc_setbits32(&regs->sysctl, SYSCTL_PEREN | SYSCTL_CKEN);
> +		return;
> +	}
> +
>  	time_out = 20;
>  	value = PRSSTAT_SDSTB;
>  	while (!(esdhc_read32(&regs->prsstat) & value)) {
> @@ -562,6 +571,7 @@ static void esdhc_clock_control(struct fsl_esdhc_priv *priv, bool enable)
>  	struct fsl_esdhc *regs = priv->esdhc_regs;
>  	u32 value;
>  	u32 time_out;
> +	u32 hostver;
>  
>  	value = esdhc_read32(&regs->sysctl);
>  
> @@ -572,6 +582,13 @@ static void esdhc_clock_control(struct fsl_esdhc_priv *priv, bool enable)
>  
>  	esdhc_write32(&regs->sysctl, value);
>  
> +	/* Only newer eSDHC controllers set PRSSTAT_SDSTB flag */
> +	hostver = esdhc_read32(&priv->esdhc_regs->hostver);
> +	if (HOSTVER_VENDOR(hostver) <= VENDOR_V_22) {
> +		udelay(10000);
> +		return;
> +	}
> +
>  	time_out = 20;
>  	value = PRSSTAT_SDSTB;
>  	while (!(esdhc_read32(&regs->prsstat) & value)) {