Re: UHS-1 cards with iMX6Q

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Fri, Feb 07, 2014 at 11:59:23PM +0800, Shawn Guo wrote:
> On Fri, Feb 07, 2014 at 03:29:51PM +0000, Russell King - ARM Linux wrote:
> > Hi,
> > 
> > I have a Samsung 8GB UHS-1 card which I'm trying with iMX6Q, and it's
> > not behaving very well with the voltage switch.  With MMC debugging
> > enabled - and augmented with additional debug for the ESDHC_VENDOR
> > register, I'm seeing this with 3.14-rc1:
> > 
> > [    2.771270] mmc1: starting CMD11 arg 00000000 flags 00000015
> > [    2.771575] sdhci [sdhci_irq()]: *** mmc1 got interrupt: 0x00000080
> > [    2.771613] sdhci [sdhci_irq()]: *** mmc1 got interrupt: 0x00000001
> > [    2.771632] mmc1: req done (CMD11): 0: 00000320 00000000 00000000 00000000
> > [    2.772669] mmc1: clock 0Hz busmode 2 powermode 2 cs 0 Vdd 21 width 0 timing 0
> > [    2.772679] mmc1: clearing ESDHC_VENDOR_SPEC_FRC_SDCLK_ON
> > [    2.772687] mmc1: ESDHC_VENDOR_SPEC_VSELECT is clear
> > [    2.772695] mmc1: clearing ESDHC_VENDOR_SPEC_VSELECT
> > [    2.772703] mmc1: clearing ESDHC_VENDOR_SPEC_FRC_SDCLK_ON
> > [    2.772713] sdhci-esdhc-imx 2194000.usdhc: change pinctrl state for uhs 0
> > [    2.772719] mmc1: clearing ESDHC_VENDOR_SPEC_FRC_SDCLK_ON
> > [    2.772729] mmc1: ESDHC_VENDOR_SPEC_VSELECT is clear
> > [    2.772735] mmc1: setting ESDHC_VENDOR_SPEC_VSELECT
> > [    2.778276] mmc1: ESDHC_VENDOR_SPEC_VSELECT is sett
> > [    2.786482] mmc1: clock 400000Hz busmode 2 powermode 2 cs 0 Vdd 21 width 0 timing 0
> > [    2.786502] sdhci-esdhc-imx 2194000.usdhc: desired SD clock: 400000, actual: 386718
> > [    2.786511] mmc1: setting ESDHC_VENDOR_SPEC_FRC_SDCLK_ON
> > [    2.787515] mmc1: ESDHC_VENDOR_SPEC_VSELECT is sett
> > [    2.787522] mmc1: setting ESDHC_VENDOR_SPEC_VSELECT
> > [    2.787529] mmc1: clearing ESDHC_VENDOR_SPEC_FRC_SDCLK_ON
> > [    2.787536] sdhci-esdhc-imx 2194000.usdhc: change pinctrl state for uhs 0
> > [    2.787548] sdhci-esdhc-imx 2194000.usdhc: desired SD clock: 400000, actual: 386718
> > [    2.787554] mmc1: setting ESDHC_VENDOR_SPEC_FRC_SDCLK_ON
> > [    2.789560] mmc1: card failed to indicate switch to low voltage mode
> > 
> > This appears to correspond with the sequence:
> > 
> > CMD11 -> clock off -> set vselect -> clock on -> clock off ->
> > set pinctrl -> clock on -> test D[3:0]
> > 
> > which appears not to be the expected sequence - the expected sequence
> > should be:
> > 
> > CMD11 -> clock off -> set vselect -> clock on -> test D[3:0]
> > 
> > maybe with the setting of the IOMUX settings somewhere in there -
> > probably at the point where the clock is off - the additional clock
> > off/clock on step looks to me incorrect.
> > 
> > In any case, I've also augmented the other failure paths in
> > mmc_set_signal_voltage(), and it's always this one (the last step)
> > which fails:
> > 
> >         if (host->ops->card_busy && host->ops->card_busy(host)) {
> >                 pr_debug("%s: card failed to indicate switch to low voltage mode\n",
> >                          mmc_hostname(host));
> >                 err = -EAGAIN;
> >         }
> > 
> > Any ideas?
> 
> I'm not sure if it's the cause or you have it set up or not, but I
> remember that we need to have 3 pinctrl states for 50MHz, 100MHz and
> 200MHz to get UHS card to work.  You can look at
> arch/arm/boot/dts/imx6qdl-sabreauto.dtsi for example.

Yes, you need those before the voltage switch is even attempted - I have
all that in place.  Lack of the pinctrl states disables 1.8V support:

        /* sdr50 and sdr104 needs work on 1.8v signal voltage */
        if ((boarddata->support_vsel) && esdhc_is_usdhc(imx_data)) {
                imx_data->pins_100mhz = pinctrl_lookup_state(imx_data->pinctrl,
                                                ESDHC_PINCTRL_STATE_100MHZ);
                imx_data->pins_200mhz = pinctrl_lookup_state(imx_data->pinctrl,
                                                ESDHC_PINCTRL_STATE_200MHZ);
                if (IS_ERR(imx_data->pins_100mhz) ||
                                IS_ERR(imx_data->pins_200mhz)) {
                        dev_warn(mmc_dev(host->mmc),
                                "could not get ultra high speed state, work on $                        /* fall back to not support uhs by specify no 1.8v quir$                        host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
                }
        } else {
                host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
        }

Here's the latest extract from DT for this:

&iomuxc {
        cubox_i {
                pinctrl_cubox_i_usdhc2_aux: cubox-i-usdhc2-aux {
                        fsl,pins = <
                                MX6QDL_PAD_GPIO_4__GPIO1_IO04    0x1f071
                                MX6QDL_PAD_KEY_ROW1__SD2_VSELECT 0x1b071
                        >;
                };

                pinctrl_cubox_i_usdhc2: cubox-i-usdhc2 {
                        fsl,pins = <
                                MX6QDL_PAD_SD2_CMD__SD2_CMD    0x17059
                                MX6QDL_PAD_SD2_CLK__SD2_CLK    0x10059
                                MX6QDL_PAD_SD2_DAT0__SD2_DATA0 0x17059
                                MX6QDL_PAD_SD2_DAT1__SD2_DATA1 0x17059
                                MX6QDL_PAD_SD2_DAT2__SD2_DATA2 0x17059
                                MX6QDL_PAD_SD2_DAT3__SD2_DATA3 0x17059
                        >;
                };

                pinctrl_cubox_i_usdhc2_100mhz: cubox-i-usdhc2-100mhz {
                        fsl,pins = <
                                MX6QDL_PAD_SD2_CMD__SD2_CMD    0x170b9
                                MX6QDL_PAD_SD2_CLK__SD2_CLK    0x100b9
                                MX6QDL_PAD_SD2_DAT0__SD2_DATA0 0x170b9
                                MX6QDL_PAD_SD2_DAT1__SD2_DATA1 0x170b9
                                MX6QDL_PAD_SD2_DAT2__SD2_DATA2 0x170b9
                                MX6QDL_PAD_SD2_DAT3__SD2_DATA3 0x170b9
                        >;
                };

                pinctrl_cubox_i_usdhc2_200mhz: cubox-i-usdhc2-200mhz {
                        fsl,pins = <
                                MX6QDL_PAD_SD2_CMD__SD2_CMD    0x170f9
                                MX6QDL_PAD_SD2_CLK__SD2_CLK    0x100f9
                                MX6QDL_PAD_SD2_DAT0__SD2_DATA0 0x170f9
                                MX6QDL_PAD_SD2_DAT1__SD2_DATA1 0x170f9
                                MX6QDL_PAD_SD2_DAT2__SD2_DATA2 0x170f9
                                MX6QDL_PAD_SD2_DAT3__SD2_DATA3 0x170f9
                        >;
                };
        };
};

&usdhc2 {
        pinctrl-names = "default", "state_100mhz", "state_200mhz";
        pinctrl-0 = <&pinctrl_cubox_i_usdhc2_aux &pinctrl_cubox_i_usdhc2>;
        pinctrl-1 = <&pinctrl_cubox_i_usdhc2_aux &pinctrl_cubox_i_usdhc2_100mhz>;
        pinctrl-2 = <&pinctrl_cubox_i_usdhc2_aux &pinctrl_cubox_i_usdhc2_200mhz>;
        vmmc-supply = <&reg_3p3v>;
        cd-gpios = <&gpio1 4 0>;
        status = "okay";
};

The VSELECT pin drives an external switch which supplies either 3.3V or
1.8V to the card and NVCC_SD2.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".