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Subject: Re: [PATCH v3 1/6] mmc: sdhci-esdhc-imx: add imx7d support and support HS400

On Wed, Aug 05, 2015 at 03:39:29PM +0800, Chen Haibo-B51421 wrote:
>
>
> > -----Original Message-----
> > From: Dong Aisheng [mailto:[email protected]]
> > Sent: Monday, August 03, 2015 8:10 PM
> > To: Chen Haibo-B51421
> > Cc: [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]; [email protected];
> > [email protected]; [email protected]; [email protected];
> > [email protected]; Estevam Fabio-R49496; [email protected];
> > [email protected]; [email protected];
> > [email protected]
> > Subject: Re: [PATCH v3 1/6] mmc: sdhci-esdhc-imx: add imx7d support and
> > support HS400
> >
> > On Sun, Aug 02, 2015 at 04:59:04PM +0800, Chen Haibo-B51421 wrote:
> > >
> > >
> > > > -----Original Message-----
> > > > From: Dong Aisheng [mailto:[email protected]]
> > > > Sent: Friday, July 31, 2015 10:15 PM
> > > > To: Chen Haibo-B51421
> > > > Cc: [email protected]; [email protected]; [email protected];
> > > > [email protected]; [email protected];
> > > > [email protected];
> > > > [email protected]; [email protected];
> > > > [email protected]; [email protected]; Estevam
> > > > Fabio-R49496; Dong Aisheng-B29396; [email protected];
> > > > [email protected]; linux-arm- [email protected];
> > > > [email protected]
> > > > Subject: Re: [PATCH v3 1/6] mmc: sdhci-esdhc-imx: add imx7d support
> > > > and support HS400
> > > >
> > > > On Wed, Jul 29, 2015 at 05:03:52PM +0800, Haibo Chen wrote:
> > > > > The imx7d usdhc is derived from imx6sx, the difference is that
> > > > > imx7d support HS400.
> > > > >
> > > > > So introduce a new compatible string for imx7d and add HS400
> > > > > support for imx7d usdhc.
> > > > >
> > > > > Signed-off-by: Haibo Chen <[email protected]>
> > > > > ---
> > > > > drivers/mmc/host/sdhci-esdhc-imx.c | 66
> > > > > ++++++++++++++++++++++++++++++++++++++
> > > > > 1 file changed, 66 insertions(+)
> > > > >
> > > > > diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c
> > > > > b/drivers/mmc/host/sdhci-esdhc-imx.c
> > > > > index c6b9f64..b441eed 100644
> > > > > --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> > > > > +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> > > > > @@ -44,6 +44,7 @@
> > > > > #define ESDHC_MIX_CTRL_EXE_TUNE (1 << 22)
> > > > > #define ESDHC_MIX_CTRL_SMPCLK_SEL (1 << 23)
> > > > > #define ESDHC_MIX_CTRL_FBCLK_SEL (1 << 25)
> > > > > +#define ESDHC_MIX_CTRL_HS400_EN (1 << 26)
> > > > > /* Bits 3 and 6 are not SDHCI standard definitions */
> > > > > #define ESDHC_MIX_CTRL_SDHCI_MASK 0xb7
> > > > > /* Tuning bits */
> > > > > @@ -60,6 +61,16 @@
> > > > > #define ESDHC_TUNE_CTRL_MIN 0
> > > > > #define ESDHC_TUNE_CTRL_MAX ((1 << 7) - 1)
> > > > >
> > > > > +/* strobe dll register */
> > > > > +#define ESDHC_STROBE_DLL_CTRL 0x70
> > > > > +#define ESDHC_STROBE_DLL_CTRL_ENABLE (1 << 0)
> > > > > +#define ESDHC_STROBE_DLL_CTRL_RESET (1 << 1)
> > > > > +#define ESDHC_STROBE_DLL_CTRL_SLV_DLY_TARGET_SHIFT 3
> > > > > +
> > > > > +#define ESDHC_STROBE_DLL_STATUS 0x74
> > > > > +#define ESDHC_STROBE_DLL_STS_REF_LOCK (1 << 1)
> > > > > +#define ESDHC_STROBE_DLL_STS_SLV_LOCK 0x1
> > > > > +
> > > > > #define ESDHC_TUNING_CTRL 0xcc
> > > > > #define ESDHC_STD_TUNING_EN (1 << 24)
> > > > > /* NOTE: the minimum valid tuning start tap for mx6sl is 1 */ @@
> > > > > -120,6 +131,8 @@
> > > > > #define ESDHC_FLAG_ERR004536 BIT(7)
> > > > > /* The IP supports HS200 mode */
> > > > > #define ESDHC_FLAG_HS200 BIT(8)
> > > > > +/* The IP supports HS400 mode */
> > > > > +#define ESDHC_FLAG_SUP_HS400 BIT(9)
> > > > >
> > > > > struct esdhc_soc_data {
> > > > > u32 flags;
> > > > > @@ -156,6 +169,12 @@ static struct esdhc_soc_data usdhc_imx6sx_data
> > = {
> > > > > | ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_HS200, };
> > > > >
> > > > > +static struct esdhc_soc_data usdhc_imx7d_data = {
> > > > > + .flags = ESDHC_FLAG_USDHC | ESDHC_FLAG_STD_TUNING
> > > > > + | ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_HS200
> > > > > + | ESDHC_FLAG_SUP_HS400,
> > > > > +};
> > > > > +
> > > > > struct pltfm_imx_data {
> > > > > u32 scratchpad;
> > > > > struct pinctrl *pinctrl;
> > > > > @@ -199,6 +218,7 @@ static const struct of_device_id
> > > > > imx_esdhc_dt_ids[]
> > > > = {
> > > > > { .compatible = "fsl,imx6sx-usdhc", .data =
> > &usdhc_imx6sx_data, },
> > > > > { .compatible = "fsl,imx6sl-usdhc", .data =
> > &usdhc_imx6sl_data, },
> > > > > { .compatible = "fsl,imx6q-usdhc", .data =
> > &usdhc_imx6q_data, },
> > > > > + { .compatible = "fsl,imx7d-usdhc", .data =
> > &usdhc_imx7d_data, },
> > > > > { /* sentinel */ }
> > > > > };
> > > > > MODULE_DEVICE_TABLE(of, imx_esdhc_dt_ids); @@ -274,6 +294,10 @@
> > > > > static u32 esdhc_readl_le(struct sdhci_host *host, int reg)
> > > > > val = SDHCI_SUPPORT_DDR50 |
> > SDHCI_SUPPORT_SDR104
> > > > > | SDHCI_SUPPORT_SDR50
> > > > > | SDHCI_USE_SDR50_TUNING;
> > > > > +
> > > > > + /* imx7d does not have a support_hs400 register,
> > fake
> > > > one */
> > > >
> > > > You could remove this line.
> > > > It's bit, not register and i think no need such comment.
> > > >
> > > > > + if (imx_data->socdata->flags &
> > ESDHC_FLAG_SUP_HS400)
> > > > > + val |= SDHCI_SUPPORT_HS400;
> > > > > }
> > > > > }
> > > > >
> > > > > @@ -774,6 +798,7 @@ static int esdhc_change_pinstate(struct
> > > > > sdhci_host
> > > > *host,
> > > > > break;
> > > > > case MMC_TIMING_UHS_SDR104:
> > > > > case MMC_TIMING_MMC_HS200:
> > > > > + case MMC_TIMING_MMC_HS400:
> > > > > pinctrl = imx_data->pins_200mhz;
> > > > > break;
> > > > > default:
> > > > > @@ -784,6 +809,30 @@ static int esdhc_change_pinstate(struct
> > > > > sdhci_host
> > > > *host,
> > > > > return pinctrl_select_state(imx_data->pinctrl, pinctrl); }
> > > > >
> > > > > +static void esdhc_set_strobe_dll(struct sdhci_host *host)
> > > >
> > > > It would be good if we can add some comments for this function for
> > > > better understand.
> > > >
> > >
> > > [haibo] okay, I will add comments here.
> > >
> > > > > +{
> > > > > + u32 v;
> > > > > +
> > > > > + /* force a reset on strobe dll */
> > > > > + writel(ESDHC_STROBE_DLL_CTRL_RESET, host->ioaddr +
> > > > ESDHC_STROBE_DLL_CTRL);
> > > > > + /*
> > > > > + * enable strobe dll ctrl and adjust the delay target
> > > > > + * for the uSDHC loopback read clock
> > > > > + */
> > > > > + v = ESDHC_STROBE_DLL_CTRL_ENABLE |
> > > > > + (7 << ESDHC_STROBE_DLL_CTRL_SLV_DLY_TARGET_SHIFT);
> > > > > + writel(v, host->ioaddr + ESDHC_STROBE_DLL_CTRL);
> > > > > + /* wait 1us to make sure strobe dll status register stable */
> > > > > + udelay(1);
> > > > > + v = readl(host->ioaddr + ESDHC_STROBE_DLL_STATUS);
> > > > > + if (!(v & ESDHC_STROBE_DLL_STS_REF_LOCK))
> > > > > + dev_warn(mmc_dev(host->mmc),
> > > > > + "warning! HS400 strobe DLL status REF not
> > lock!\n");
> > > > > + if (!(v & ESDHC_STROBE_DLL_STS_SLV_LOCK))
> > > > > + dev_warn(mmc_dev(host->mmc),
> > > > > + "warning! HS400 strobe DLL status SLV not
> > lock!\n"); }
> > > > > +
> > > > > static void esdhc_set_uhs_signaling(struct sdhci_host *host,
> > > > > unsigned
> > > > > timing) {
> > > > > struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); @@
> > > > > -795,7
> > > > > +844,13 @@ static void esdhc_set_uhs_signaling(struct sdhci_host
> > > > > +*host,
> > > > unsigned timing)
> > > > > case MMC_TIMING_UHS_SDR25:
> > > > > case MMC_TIMING_UHS_SDR50:
> > > > > case MMC_TIMING_UHS_SDR104:
> > > > > + break;
> > > > > case MMC_TIMING_MMC_HS200:
> > > > > + /* disable ddr mode and disable HS400 mode */
> > > > > + writel(readl(host->ioaddr + ESDHC_MIX_CTRL) &
> > > > > + ~(ESDHC_MIX_CTRL_DDREN | ESDHC_MIX_CTRL_HS400_EN),
> > > > > + host->ioaddr + ESDHC_MIX_CTRL);
> > > > > + imx_data->is_ddr = 0;
> > > > > break;
> > > > > case MMC_TIMING_UHS_DDR50:
> > > > > case MMC_TIMING_MMC_DDR52:
> > > > > @@ -813,6 +868,14 @@ static void esdhc_set_uhs_signaling(struct
> > > > sdhci_host *host, unsigned timing)
> > > > > writel(v, host->ioaddr + ESDHC_DLL_CTRL);
> > > > > }
> > > > > break;
> > > > > + case MMC_TIMING_MMC_HS400:
> > > > > + writel(readl(host->ioaddr + ESDHC_MIX_CTRL) |
> > > > > + ESDHC_MIX_CTRL_DDREN |
> > ESDHC_MIX_CTRL_HS400_EN,
> > > > > + host->ioaddr + ESDHC_MIX_CTRL);
> > > > > + imx_data->is_ddr = 1;
> > > > > + if (host->clock == 200000000)
> > > >
> > > > I can't remember, but could this be a range required by SoC?
> > >
> > > [haibo]we should set strobe_dll only when the host clock is 200MHz. For
> > other condition, no need to do this.
> > >
> >
> > It is not quite make sense for only 200Mhz clock here.
> >
> > First, shall we check host->mmc->actual_clock instead of host->clock?
> > That is the real clock frequency the controller is working on.
> >
> >
> > Second, even MMC core requests to set 200Mhz clock for HS400, the real
> > clock controller working on may be less than 200Mhz which depends on the
> > uSDHC root clock capability.
> > e.g. it may be 192Mhz if the parent is 384Mhz or less.
> > If that, do we need call strobe_dll too?
> >
>
> [haibo] according to IC team feedback, when we use HS400 mode in high frequency, like:
> close to 200Mhz, including 192Mhz, we should call strobe_dll. When the eMMC clock is around
> 100Mhz, like 98Mhz, no need to call strobe_dll, I have test this, eMMC can read normally.
>
> When the card clock become higher, each clock cycle becomes shorter. When each clock cycle is short
> enough, the time delay between CLK and strobe_data_clock maybe larger than one clock cycle, so the CLk
> and strobe_data_clock misaligned, then read error shows up. (here CLK means the clock host supply to card,
> and strobe_data_clock means the clock generated by device which feedback to host for data read in HS400 mode).
>
> So can we call strobe_dll when the card clock is over 100Mhz?
>

Yes, i'm okay with it.
You could define a macro for it like:
/* a higher clock frequency than this rate requires strobe dll control */
#define ESDHC_STROBE_DLL_CLK_FREQ 100000000
if (host->mmc->actual_clock > ESDHC_STROBE_DLL_CLK_FREQ)
strobe_dll();

You can also get this as a separate function call which seems better.

Regards
Dong Aisheng

>
> > Can you check above two concerns?
> >
> > Regards
> > Dong Aisheng
> >
> > > >
> > > > > + esdhc_set_strobe_dll(host);
> > > > > + break;
> > > > > }
> > > > >
> > > > > esdhc_change_pinstate(host, timing); @@ -1100,6 +1163,9 @@
> > > > > static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
> > > > > if (imx_data->socdata->flags & ESDHC_FLAG_ERR004536)
> > > > > host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> > > > >
> > > > > + if (imx_data->socdata->flags & ESDHC_FLAG_SUP_HS400)
> > > > > + host->quirks2 |= SDHCI_QUIRK2_CAPS_BIT63_FOR_HS400;
> > > > > +
> > > > > if (of_id)
> > > > > err = sdhci_esdhc_imx_probe_dt(pdev, host, imx_data);
> > > > > else
> > > > > --
> > > > > 1.9.1
> > > > >
> > > >
> > > > Regards
> > > > Dong Aisheng