[PATCH v2 3/4] arm64: add support for i.MX8M EVK board

[Bough Chen]

>-----Original Message-----
>From: Lucas Stach [mailto:l.stach at pengutronix.de]
>Sent: 2018年2月23日 23:46
>To: Juergen Borleis <jbe at pengutronix.de>; kernel at pengutronix.de
>Cc: Shawn Guo <shawnguo at kernel.org>; Mark Rutland
><mark.rutland at arm.com>; devicetree at vger.kernel.org; Baruch Siach
><baruch at tkos.co.il>; Catalin Marinas <catalin.marinas at arm.com>; Will
>Deacon <will.deacon at arm.com>; patchwork-lst at pengutronix.de; Rob Herring
><robh+dt at kernel.org>; dl-linux-imx <linux-imx at nxp.com>; Fabio Estevam
><fabio.estevam at nxp.com>; A.s. Dong <aisheng.dong at nxp.com>;
>linux-arm-kernel at lists.infradead.org
>Subject: Re: [PATCH v2 3/4] arm64: add support for i.MX8M EVK board
>
>Am Freitag, den 23.02.2018, 16:30 +0100 schrieb Juergen Borleis:
>> On Friday 23 February 2018 16:03:53 Shawn Guo wrote:
>> > On Thu, Feb 01, 2018 at 07:31:25PM +0100, Lucas Stach wrote:
>> > > +&usdhc1 {
>> > > +   pinctrl-names = "default", "state_100mhz", "state_200mhz";
>> > > +   pinctrl-0 = <&pinctrl_usdhc1_cd_reset>,
>> <&pinctrl_usdhc1_clk_strobe>,
>> > > +               <&pinctrl_usdhc1_data>;
>> > > +   pinctrl-1 = <&pinctrl_usdhc1_cd_reset>,
>> > > +               <&pinctrl_usdhc1_clk_strobe_100mhz>,
>> > > +               <&pinctrl_usdhc1_data_100mhz>;
>> > > +   pinctrl-2 = <&pinctrl_usdhc1_cd_reset>,
>> > > +               <&pinctrl_usdhc1_clk_strobe_200mhz>,
>> > > +               <&pinctrl_usdhc1_data_200mhz>;
>> > > +   vqmmc-supply = <&sw4_reg>;
>> > > +   bus-width = <8>;
>> > > +   non-removable;
>> > > +   no-sd;
>> > > +   no-sdio;
>> > > +   status = "okay";
>> > > +};
>> >

EMMC do not need cd pin, and I notice that pinctrl_usdhc1_cd_reset also contains a usdhc2 pad, this is wrong. So please remove pinctrl_usdhc1_cd_reset. 
EMMC I/O voltage is fixed to 1.8v so I think no need to add vqmmc-supply, can remove this property here.
For pinctrl_usdhc1_clk_strobe, clock pad need to be pull down, otherwise you will meet data crc error in hs400 mode.

Best Regards,
Bough Chen

>> > I'm not sure it can be enabled right now.  Per my testing, eMMC is
>> not
>> > working yet.
>> >
>> > [    0.879756] mmc0: Switching to 3.3V signalling voltage failed [
>> > 0.913587] mmc0: SDHCI controller on 30b40000.usdhc
>> [30b40000.usdhc]
>> > using ADMA ...
>> > [    1.007628] mmc0: switch to high-speed from hs200 failed, err:-
>> 110
>> > [    1.013873] mmc0: error -110 whilst initialising MMC card [
>> > 1.020639] mmc0: Switching to 3.3V signalling voltage failed ...
>> > [    1.132462] mmc0: switch to high-speed from hs200 failed, err:-
>> 110
>> > [    1.138674] mmc0: error -110 whilst initialising MMC card [
>> > 1.145394] mmc0: Switching to 3.3V signalling voltage failed [
>> > 1.268367] mmc0: switch to high-speed from hs200 failed, err:-
>> 110
>> > [    1.274576] mmc0: error -110 whilst initialising MMC card [
>> > 1.281291] mmc0: Switching to 3.3V signalling voltage failed [
>> > 1.440708] mmc0: switch to high-speed from hs200 failed, err:-
>> 110
>> > [    1.446919] mmc0: error -110 whilst initialising MMC card
>> >
>> > Or am I missing anything?
>>
>> Property "no-1-8-v;" if no 1.8 V is available?
>
>The issue is the other way around: the eMMC is hardwired to 1.8V IO voltage
>(which is fine per eMMC spec), so it can't switch to 3.3V mode.
>
>Regards,
>Lucas