[U-Boot] [PATCH] mmc: fsl_esdhc: Add support for DDR mode

[Volodymyr Riazantsev]

Hi Pantelis,

On Mon, Jan 19, 2015 at 10:47 AM, Pantelis Antoniou
<pantelis.antoniou at gmail.com> wrote:
>
> Hi Volodymyr,
>
> > On Jan 14, 2015, at 22:46 , Volodymyr Riazantsev <volodymyr.riazantsev at globallogic.com> wrote:
> >
> > Add support of the DDR mode for eSDHC driver.
> > Enable it for i.MX6 SoC family only.
> >
> > Change-Id: Ie27a945c9fe79d044cc886e269b60747f1744116
> > Signed-off-by: Volodymyr Riazantsev <volodymyr.riazantsev at globallogic.com>
> > ---
> > drivers/mmc/fsl_esdhc.c | 8 ++++++--
> > include/fsl_esdhc.h     | 1 +
> > 2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
> > index c55eb28..abec45f 100644
> > --- a/drivers/mmc/fsl_esdhc.c
> > +++ b/drivers/mmc/fsl_esdhc.c
> > @@ -319,7 +319,8 @@ esdhc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data)
> >       esdhc_write32(&regs->cmdarg, cmd->cmdarg);
> > #if defined(CONFIG_FSL_USDHC)
> >       esdhc_write32(&regs->mixctrl,
> > -     (esdhc_read32(&regs->mixctrl) & 0xFFFFFF80) | (xfertyp & 0x7F));
> > +     (esdhc_read32(&regs->mixctrl) & 0xFFFFFF80) | (xfertyp & 0x7F)
> > +                     | (mmc->ddr_mode ? XFERTYP_DDREN : 0));
> >       esdhc_write32(&regs->xfertyp, xfertyp & 0xFFFF0000);
> > #else
> >       esdhc_write32(&regs->xfertyp, xfertyp);
> > @@ -442,7 +443,7 @@ static void set_sysctl(struct mmc *mmc, uint clock)
> >               if ((sdhc_clk / (div * pre_div)) <= clock)
> >                       break;
> >
> > -     pre_div >>= 1;
> > +     pre_div >>= mmc->ddr_mode ? 2 : 1;
> >       div -= 1;
> >
> >       clk = (pre_div << 8) | (div << 4);
> > @@ -601,6 +602,9 @@ int fsl_esdhc_initialize(bd_t *bis, struct fsl_esdhc_cfg *cfg)
> >       }
> >
> >       cfg->cfg.host_caps = MMC_MODE_4BIT | MMC_MODE_8BIT | MMC_MODE_HC;
> > +#ifdef CONFIG_MX6
> > +     cfg->cfg.host_caps |= MMC_MODE_DDR_52MHz;
> > +#endif
> >
> >       if (cfg->max_bus_width > 0) {
> >               if (cfg->max_bus_width < 8)
> > diff --git a/include/fsl_esdhc.h b/include/fsl_esdhc.h
> > index c1b6648..313fa1e 100644
> > --- a/include/fsl_esdhc.h
> > +++ b/include/fsl_esdhc.h
> > @@ -108,6 +108,7 @@
> > #define XFERTYP_RSPTYP_48_BUSY        0x00030000
> > #define XFERTYP_MSBSEL                0x00000020
> > #define XFERTYP_DTDSEL                0x00000010
> > +#define XFERTYP_DDREN                0x00000008
> > #define XFERTYP_AC12EN                0x00000004
> > #define XFERTYP_BCEN          0x00000002
> > #define XFERTYP_DMAEN         0x00000001
> > --
> > 2.2.0
>
> The patch is OK, but I don’t like the use of CONFIG_MX6 for enabling it.
> The meaning is that the MMC IP block in MX6 supports DDR mode, so make it a quirk
> that’s enabled for MX6.
>
> Subsequent SoCs might use the same mode, so I don’t like having to do endless defines
> of SoC families.
>
> Please rework.
>
> Regards
>
> — Pantelis

Thank you for the comments,
   I've reworked patch for get ability to enable this feature via
   separate configuration flag. I put that flag into common mx6
   header, otherwise we have to enable it for each separate mx6 board.
   I didn't found way to run-time check for this feature on the
initialization path.

Best regards,
   Volodymyr.