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

[Oleksandr Suvorov <oleksandr.suvorov@foundries.io>]

Hi Igor,

On Wed, Sep 8, 2021 at 5:42 PM Igor Opaniuk <igor.opaniuk@foundries.io> wrote:
>
> Hi Oleksandr,
>
> On Tue, Aug 31, 2021 at 8:49 PM Oleksandr Suvorov
> <oleksandr.suvorov@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@foundries.io>
> > Reviewed-by: Fabio Estevam <festevam@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.

Thank you, fixed!

> >
> >                 /*
> >                  * 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@foundries.io>
>
> --
> Best regards - Freundliche Grüsse - Meilleures salutations
>
> Igor Opaniuk
> Embedded Software Engineer
> T:  +380 938364067
> E: igor.opaniuk@foundries.io
> W: www.foundries.io



-- 
Best regards,

Oleksandr Suvorov
Software Engineer
W: www.foundries.io