On Fri, May 25, 2018 at 7:16 AM, Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote:
> Am Donnerstag, den 24.05.2018, 20:01 -0700 schrieb Andrey Smirnov:
>> Make sure that MX51_PAD_GPIO1_1 does not remain configure as
>> ALT0/SD1_WP (it is out of reset). This is needed because of external
>> pull-up resistor attached to that pad that, when left unchanged, will
>> drive SD1_WP high preventing eSDHC1/eMMC from working correctly.
>>
>> To fix that add a pinmux configuration line configureing the pad to
>> function as a GPIO. While we are at it, add a corresponding input GPIO
>> hog in an effort to minimize current consumption.
>
> Enabling the input part of the pad also consumes (a small amount of)
> power, if you are after minimizing power consumption, better configure
> the pin as output and drive it in the pull direction.
>
Sure, sounds good, will do in v2.
>>
>> > Cc: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
>> > Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
>> > Cc: Fabio Estevam <fabio.estevam@xxxxxxx>
>> > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
>> > Cc: Chris Healy <cphealy@xxxxxxxxx>
>> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>
>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
>> Cc: devicetree@xxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> > Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
>> ---
>> arch/arm/boot/dts/imx51-zii-rdu1.dts | 28 ++++++++++++++++++++++++++++
>> 1 file changed, 28 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/imx51-zii-rdu1.dts b/arch/arm/boot/dts/imx51-zii-rdu1.dts
>> index df9eca94d812..d484e7e46b27 100644
>> --- a/arch/arm/boot/dts/imx51-zii-rdu1.dts
>> +++ b/arch/arm/boot/dts/imx51-zii-rdu1.dts
>> @@ -476,6 +476,17 @@
>> > status = "okay";
>> };
>>
>> +&gpio1 {
>> > + unused-sd3-wp-gpio {
>> > + /*
>> > + * See pinctrl_esdhc1 below for more details on this
>> > + */
>> > + gpio-hog;
>> > + gpios = <1 GPIO_ACTIVE_HIGH>;
>> > + input;
>> > + };
>> +};
>> +
>> &i2c2 {
>> > pinctrl-names = "default";
>> > pinctrl-0 = <&pinctrl_i2c2>;
>> @@ -660,6 +671,23 @@
>> > > MX51_PAD_SD1_DATA1__SD1_DATA1 0x20d5
>> > > MX51_PAD_SD1_DATA2__SD1_DATA2 0x20d5
>> > > MX51_PAD_SD1_DATA3__SD1_DATA3 0x20d5
>> > + /*
>> > + * GPIO1_1 is not directly used by eSDHC1 in
>> > + * any capacity, but earlier versions of RDU1
>> > + * used that pin as WP GPIO for eSDHC3 and
>> > + * because of that that pad has an external
>> > + * pull-up resistor. This is problematic
>> > + * because out of reset the pad is configured
>> > + * as ALT0 which serves as SD1_WP, which, when
>> > + * pulled high by and external pull-up, will
>> > + * inhibit execution of any write request to
>> > + * attached eMMC device.
>> > + *
>> > + * To avoid this problem we configure the pad
>> > + * to ALT1/GPIO and avoid driving SD1_WP
>> + * signal high.
>
> Applying the patch complains about whitespace damage in the above 2
> lines.
>
My bad, sorry about that, will fix in v2.
Thanks,
Andrey Smirnov
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