[PATCH v2 2/2] mmc: sdhci-esdhc-imx: Add HS400 support for iMX7ULP

[Jaehoon Chung]

On 9/1/21 2:49 AM, Oleksandr Suvorov wrote:
> Import HS400 support for iMX7ULP B0 from the Linux kernel:
> 
> 2eaf5a533afd ("mmc: sdhci-esdhc-imx: Add HS400 support for iMX7ULP")
> 
> According to IC suggest, need to clear the STROBE_DLL_CTRL_RESET
> before any setting of STROBE_DLL_CTRL register.
> 
> USDHC has register bits(bit[27~20] of register STROBE_DLL_CTRL)
> for slave sel value. If this register bits value is 0,  it needs
> 256 ref_clk cycles to update slave sel value. IC suggest to set
> bit[27~20] to 0x4, it only need 4 ref_clk cycle to update slave
> sel value. This will short the lock time of slave.
> 
> i.MX7ULP B0 will need more time to lock the REF and SLV, so change
> to add 5us delay.
> 
> Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov at foundries.io>
> Reviewed-by: Fabio Estevam <festevam at gmail.com>


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

Best Regards,
Jaehoon Chung

> ---
> 
> Changes in v2:
> - fixed Series-notes record.
> - added Reviewed-by records.
> 
>  drivers/mmc/fsl_esdhc_imx.c | 11 ++++++++---
>  include/fsl_esdhc_imx.h     |  1 +
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/fsl_esdhc_imx.c b/drivers/mmc/fsl_esdhc_imx.c
> index 6c8f77f9ee..569f099d9b 100644
> --- a/drivers/mmc/fsl_esdhc_imx.c
> +++ b/drivers/mmc/fsl_esdhc_imx.c
> @@ -727,17 +727,21 @@ static void esdhc_set_strobe_dll(struct mmc *mmc)
>  
>  	if (priv->clock > ESDHC_STROBE_DLL_CLK_FREQ) {
>  		esdhc_write32(&regs->strobe_dllctrl, ESDHC_STROBE_DLL_CTRL_RESET);
> +		/* clear the reset bit on strobe dll before any setting */
> +		esdhc_write32(&regs->strobe_dllctrl, 0);
> +
>  
>  		/*
>  		 * enable strobe dll ctrl and adjust the delay target
>  		 * for the uSDHC loopback read clock
>  		 */
>  		val = ESDHC_STROBE_DLL_CTRL_ENABLE |
> +			ESDHC_STROBE_DLL_CTRL_SLV_UPDATE_INT_DEFAULT |
>  			(priv->strobe_dll_delay_target <<
>  			 ESDHC_STROBE_DLL_CTRL_SLV_DLY_TARGET_SHIFT);
>  		esdhc_write32(&regs->strobe_dllctrl, val);
> -		/* wait 1us to make sure strobe dll status register stable */
> -		mdelay(1);
> +		/* wait 5us to make sure strobe dll status register stable */
> +		mdelay(5);
>  		val = esdhc_read32(&regs->strobe_dllstat);
>  		if (!(val & ESDHC_STROBE_DLL_STS_REF_LOCK))
>  			pr_warn("HS400 strobe DLL status REF not lock!\n");
> @@ -1708,7 +1712,8 @@ static struct esdhc_soc_data usdhc_imx7d_data = {
>  
>  static struct esdhc_soc_data usdhc_imx7ulp_data = {
>  	.flags = ESDHC_FLAG_USDHC | ESDHC_FLAG_STD_TUNING
> -			| ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_HS200,
> +			| ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_HS200
> +			| ESDHC_FLAG_HS400,
>  };
>  
>  static struct esdhc_soc_data usdhc_imx8qm_data = {
> diff --git a/include/fsl_esdhc_imx.h b/include/fsl_esdhc_imx.h
> index 45ed635a77..12e9163382 100644
> --- a/include/fsl_esdhc_imx.h
> +++ b/include/fsl_esdhc_imx.h
> @@ -194,6 +194,7 @@
>  #define ESDHC_STROBE_DLL_CTRL_RESET	BIT(1)
>  #define ESDHC_STROBE_DLL_CTRL_SLV_DLY_TARGET_DEFAULT	0x7
>  #define ESDHC_STROBE_DLL_CTRL_SLV_DLY_TARGET_SHIFT	3
> +#define ESDHC_STROBE_DLL_CTRL_SLV_UPDATE_INT_DEFAULT   (4 << 20)
>  
>  #define ESDHC_STROBE_DLL_STATUS		0x74
>  #define ESDHC_STROBE_DLL_STS_REF_LOCK	BIT(1)
>