Re: [PATCH] mmc: sdhci-of-esdhc: exit HS400 properly before setting any speed mode

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

On 22/05/20 6:12 am, Yangbo Lu wrote:
> The eSDHC HS400 timing requires many specific registers setting,
> unlike other speed modes which need to set only host controller 2
> register. When driver needs to downgrade HS400 mode to other speed
> mode, the controller have to exit HS400 timing properly first.
> This patch is to support the procedure of HS400 exiting at the
> beginning of esdhc_set_uhs_signaling.
> 
> Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>

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

> ---
>  drivers/mmc/host/sdhci-of-esdhc.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
> index 5d8dd87..7c73d24 100644
> --- a/drivers/mmc/host/sdhci-of-esdhc.c
> +++ b/drivers/mmc/host/sdhci-of-esdhc.c
> @@ -1135,6 +1135,40 @@ static int esdhc_execute_tuning(struct mmc_host *mmc, u32 opcode)
>  static void esdhc_set_uhs_signaling(struct sdhci_host *host,
>  				   unsigned int timing)
>  {
> +	u32 val;
> +
> +	/*
> +	 * There are specific registers setting for HS400 mode.
> +	 * Clean all of them if controller is in HS400 mode to
> +	 * exit HS400 mode before re-setting any speed mode.
> +	 */
> +	val = sdhci_readl(host, ESDHC_TBCTL);
> +	if (val & ESDHC_HS400_MODE) {
> +		val = sdhci_readl(host, ESDHC_SDTIMNGCTL);
> +		val &= ~ESDHC_FLW_CTL_BG;
> +		sdhci_writel(host, val, ESDHC_SDTIMNGCTL);
> +
> +		val = sdhci_readl(host, ESDHC_SDCLKCTL);
> +		val &= ~ESDHC_CMD_CLK_CTL;
> +		sdhci_writel(host, val, ESDHC_SDCLKCTL);
> +
> +		esdhc_clock_enable(host, false);
> +		val = sdhci_readl(host, ESDHC_TBCTL);
> +		val &= ~ESDHC_HS400_MODE;
> +		sdhci_writel(host, val, ESDHC_TBCTL);
> +		esdhc_clock_enable(host, true);
> +
> +		val = sdhci_readl(host, ESDHC_DLLCFG0);
> +		val &= ~(ESDHC_DLL_ENABLE | ESDHC_DLL_FREQ_SEL);
> +		sdhci_writel(host, val, ESDHC_DLLCFG0);
> +
> +		val = sdhci_readl(host, ESDHC_TBCTL);
> +		val &= ~ESDHC_HS400_WNDW_ADJUST;
> +		sdhci_writel(host, val, ESDHC_TBCTL);
> +
> +		esdhc_tuning_block_enable(host, false);
> +	}
> +
>  	if (timing == MMC_TIMING_MMC_HS400)
>  		esdhc_tuning_block_enable(host, true);
>  	else
>