On Wed, May 24, 2017 at 3:36 PM, Geert Uytterhoeven
<[email protected]> wrote:
> On Wed, May 24, 2017 at 2:57 PM, Laurent Pinchart
> <[email protected]> wrote:
>> On Wednesday 24 May 2017 13:43:34 Geert Uytterhoeven wrote:
>>> Configuration of the lcd0 pinmux group and GPIO hog for the external
>>> GPIO mux are done using a single device node, causing the "output-high"
>>> property to be applied to both. This will fail for the pinmux group,
>>> but doesn't cause any harm, as the failure is ignored silently.
>>>
>>> However, after "pinctrl: sh-pfc: propagate errors on group config", the
>>> failure will become fatal, leading to a broken display:
>>>
>>> sh-pfc e6050000.pin-controller: pin_config_group_set op failed for group
>>> 102 sh-pfc e6050000.pin-controller: Error applying setting, reverse things
>>> back sh-pfc e6050000.pin-controller: failed to select default state
>>>
>>> Split the configuration in two subnodes, and replace the GPIO hog by a
>>> pull-up pin bias to fix this.
>>>
>>> Fixes: ffd2f9a5afb730b9 ("ARM: shmobile: armadillo800eva dts: Add pinctrl
>>> and gpio-hog for lcdc0") Signed-off-by: Geert Uytterhoeven
>>> <[email protected]>
>>> ---
>>> This is a hard dependency for "pinctrl: sh-pfc: propagate errors on
>>> group config" (https://patchwork.kernel.org/patch/9186713/).
>>>
>>> Notes:
>>> 1. Just keeping the GPIO hog doesn't work, as the sh-pfc driver
>>> requires each pinctrl (sub)node to have at least one "pins" or
>>> "groups" property,
>>> 2. Keeping "output-high" doesn't work, as the sh-pfc driver does not
>>> implement PIN_CONFIG_OUTPUT.
>>>
>>> Should I fix 1 and/or 2 instead?
>>> ---
>>> arch/arm/boot/dts/r8a7740-armadillo800eva.dts | 15 +++++++++------
>>> 1 file changed, 9 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/arch/arm/boot/dts/r8a7740-armadillo800eva.dts
>>> b/arch/arm/boot/dts/r8a7740-armadillo800eva.dts index
>>> 44b335b9f035436d..7feedc86f6915654 100644
>>> --- a/arch/arm/boot/dts/r8a7740-armadillo800eva.dts
>>> +++ b/arch/arm/boot/dts/r8a7740-armadillo800eva.dts
>>> @@ -267,13 +267,16 @@
>>> };
>>>
>>> lcd0_pins: lcd0 {
>>> - groups = "lcd0_data24_0", "lcd0_lclk_1", "lcd0_sync";
>>> - function = "lcd0";
>>> + mux {
>>> + groups = "lcd0_data24_0", "lcd0_lclk_1", "lcd0_sync";
>>> + function = "lcd0";
>>> + };
>>>
>>> - /* DBGMD/LCDC0/FSIA MUX */
>>> - gpio-hog;
>>> - gpios = <176 0>;
>>> - output-high;
>>> + gpio {
>>> + /* DBGMD/LCDC0/FSIA MUX */
>>> + pins = "PORT176";
>>> + bias-pull-up;
>>
>> The signal is pulled low through a 10kΩ resistor, so a pull-up is a bit weak.
>
> According to the schematics, the resistor is not mounted.
JFTR, R67 (bottom of the PCB, 2 cm from pin 1 of unpopulated CON16)
is indeed not populated on mine.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
