Thanks for review!
Updated the programming sequence and Pushed version v3.
Thanks
Prathamesh.
> -----Original Message-----
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Sent: Thursday, December 2, 2021 8:05 PM
> To: Prathamesh Shete <pshete@xxxxxxxxxx>; ulf.hansson@xxxxxxxxxx;
> thierry.reding@xxxxxxxxx; Jonathan Hunter <jonathanh@xxxxxxxxxx>;
> p.zabel@xxxxxxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-
> tegra@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Cc: Aniruddha Tvs Rao <anrao@xxxxxxxxxx>; Suresh Mangipudi
> <smangipudi@xxxxxxxxxx>
> Subject: Re: [PATCH v2] mmc: sdhci-tegra: Fix switch to HS400ES mode
>
> External email: Use caution opening links or attachments
>
>
> On 02/12/2021 15:49, Prathamesh Shete wrote:
> > When CMD13 is sent after switching to HS400ES mode, the bus is
> > operating at either MMC_HIGH_26_MAX_DTR or MMC_HIGH_52_MAX_DTR.
> > To meet Tegra SDHCI requirement at HS400ES mode, force SDHCI interface
> > clock to MMC_HS200_MAX_DTR (200 MHz) so that host controller CAR clock
> > and the interface clock are rate matched.
> >
> > Signed-off-by: Prathamesh Shete <pshete@xxxxxxxxxx>
> > ---
> > drivers/mmc/host/sdhci-tegra.c | 43
> > ++++++++++++++++++++--------------
> > 1 file changed, 26 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-tegra.c
> > b/drivers/mmc/host/sdhci-tegra.c index 387ce9cdbd7c..ca261cce9b37
> > 100644
> > --- a/drivers/mmc/host/sdhci-tegra.c
> > +++ b/drivers/mmc/host/sdhci-tegra.c
> > @@ -354,23 +354,6 @@ static void tegra_sdhci_set_tap(struct sdhci_host
> *host, unsigned int tap)
> > }
> > }
> >
> > -static void tegra_sdhci_hs400_enhanced_strobe(struct mmc_host *mmc,
> > - struct mmc_ios *ios)
> > -{
> > - struct sdhci_host *host = mmc_priv(mmc);
> > - u32 val;
> > -
> > - val = sdhci_readl(host, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
> > -
> > - if (ios->enhanced_strobe)
> > - val |= SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
> > - else
> > - val &= ~SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
> > -
> > - sdhci_writel(host, val, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
> > -
> > -}
> > -
> > static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask) {
> > struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); @@
> > -791,6 +774,32 @@ static void tegra_sdhci_set_clock(struct sdhci_host *host,
> unsigned int clock)
> > }
> > }
> >
> > +static void tegra_sdhci_hs400_enhanced_strobe(struct mmc_host *mmc,
> > + struct mmc_ios *ios) {
> > + struct sdhci_host *host = mmc_priv(mmc);
> > + u32 val;
> > +
> > + val = sdhci_readl(host, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
> > +
> > + if (ios->enhanced_strobe)
> > + val |= SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
> > + else
> > + val &= ~SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
> > +
> > + sdhci_writel(host, val, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
> > +
> > + /*
> > + * When CMD13 is sent from mmc_select_hs400es() after
> > + * switching to HS400ES mode, the bus is operating at
> > + * either MMC_HIGH_26_MAX_DTR or MMC_HIGH_52_MAX_DTR.
> > + * To meet Tegra SDHCI requirement at HS400ES mode, force SDHCI
> > + * interface clock to MMC_HS200_MAX_DTR (200 MHz) so that host
> > + * controller CAR clock and the interface clock are rate matched.
>
> Still doesn't explain why you want to set MMC_HS200_MAX_DTR when
> ios->enhanced_strobe is false e.g. mmc_set_initial_state()
That’s a good catch. Updated the code sequence and pushed v3.
> > + */
> > + tegra_sdhci_set_clock(host, MMC_HS200_MAX_DTR); }
> > +
> > static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host
> > *host) {
> > struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> >
