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

[Igor Opaniuk]

Hi Oleksandr,

On Tue, Aug 31, 2021 at 8:49 PM Oleksandr Suvorov
<oleksandr.suvorov at foundries.io> 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>
> ---
>
> 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);
> +
minor:
additional blank line isn't needed.
>
>                 /*
>                  * 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)
> --
> 2.31.1
>

Reviewed-by: Igor Opaniuk <igor.opaniuk at foundries.io>

-- 
Best regards - Freundliche Grüsse - Meilleures salutations

Igor Opaniuk
Embedded Software Engineer
T:  +380 938364067
E: igor.opaniuk at foundries.io
W: www.foundries.io