Am Montag, den 07.11.2016, 14:17 +0100 schrieb Thierry Reding: > On Mon, Nov 07, 2016 at 06:12:43PM +0800, Chen-Yu Tsai wrote: > > On Sun, Nov 6, 2016 at 7:09 PM, Icenowy Zheng <icenowy@xxxxxxxx> wrote: > > > The enable gpio of simple-panel may be used by a simplefb or other > > > driver on the panel's display before the KMS driver get load. > > > > > > Get the GPIO as-is, so the panel won't be disabled, and the simplefb > > > can work. > > > > > > Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx> > > > --- > > > drivers/gpu/drm/panel/panel-simple.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c > > > index 113db3c..ccee4c1 100644 > > > --- a/drivers/gpu/drm/panel/panel-simple.c > > > +++ b/drivers/gpu/drm/panel/panel-simple.c > > > @@ -312,7 +312,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc) > > > return PTR_ERR(panel->supply); > > > > > > panel->enable_gpio = devm_gpiod_get_optional(dev, "enable", > > > - GPIOD_OUT_LOW); > > > + GPIOD_ASIS); > > > > The GPIO requested as-is might be in input mode. You should change the > > gpiod_set_value calls to gpiod_direction_output calls. The later also > > allows you to give an initial value. Not sure if it checks for cansleep > > like the set_value calls though. > > I'd prefer not to add gpiod_direction_output() calls outside of > ->probe(). Instead, could we make this patch be smart about taking over > from an earlier user? Could it read the current direction and value of > the GPIO and not disable it if it had previously been enabled? Seconded, the PWM backlight driver in drivers/video/backlight/pwm_bl.c already does a similar thing. > And even if we go this extra mile there's a possibility that the GPIO > was just left dangling by earlier software (or hardware) and leaving it > on would actually be worse than turning the panel off. Is this something the encoder driver should communicate to the panel? That one will know whether its atomic_reset state is enabled or disabled. regards Philipp _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
