Hi Paul,
On Thu, Nov 25, 2021 at 10:02 AM Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:
> Le jeu., nov. 25 2021 at 08:58:13 +0100, Geert Uytterhoeven
> <geert@xxxxxxxxxxxxxx> a écrit :
> > On Wed, Nov 24, 2021 at 5:31 PM H. Nikolaus Schaller
> > <hns@xxxxxxxxxxxxx> wrote:
> >> > Am 24.11.2021 um 17:21 schrieb Geert Uytterhoeven
> >> <geert@xxxxxxxxxxxxxx>:
> >> > On Wed, Nov 24, 2021 at 5:19 PM H. Nikolaus Schaller
> >> <hns@xxxxxxxxxxxxx> wrote:
> >> >>> Am 23.11.2021 um 21:10 schrieb Paul Cercueil
> >> <paul@xxxxxxxxxxxxxxx>:
> >> >>> Le mar., nov. 23 2021 at 19:13:59 +0100, H. Nikolaus Schaller
> >> <hns@xxxxxxxxxxxxx> a écrit :
> >> >>>> + assigned-clock-rates = <48000000>, <0>, <54000000>, <0>,
> >> <27000000>;
> >> >>>> };
> >> >>>> &tcu {
> >> >>>> @@ -509,6 +534,19 @@ pins_i2c4: i2c4 {
> >> >>>> bias-disable;
> >> >>>> };
> >> >>>> + pins_hdmi_ddc: hdmi_ddc {
> >> >>>> + function = "hdmi-ddc";
> >> >>>> + groups = "hdmi-ddc";
> >> >>>> + bias-disable;
> >> >>>> + };
> >> >>>> +
> >> >>>> + /* switch to PF25 as gpio driving DDC_SDA low */
> >> >>>> + pins_hdmi_ddc_unwedge: hdmi_ddc {
> >> >>>> + function = "hdmi-ddc";
> >> >>>> + groups = "hdmi-ddc";
> >> >>>> + bias-disable;
> >> >>>> + };
> >> >>>
> >> >>> Your pins_hdmi_ddc and pins_hdmi_ddc_unwedge are the exact
> >> same? You could just use the former and pass it to both pinctrl-0
> >> and pinctrl-1.
> >> >>
> >> >> This was forgotten to remove. We do not make use of the unwedge
> >> feature because I could not find out how to use pinctrl to switch
> >> this to gpio25 and drive it low.
> >> >
> >> > Using gpio-hog?
> >>
> >> well, AFAIR it activates the gpio permanently and is a propery of
> >> the gpio controller and not of pinmux.
> >
> > Yes, hogs are permanently (ignoring DT overlay tricks).
> >
> >> The driver assumes it can use pinmux state switching to drive the
> >> DDC_SDA line low on demand.
> >
> > Add an optional wedge-gpios property for switching?
>
> I think you can use a pinctrl state as well, specifying the pin and the
> 'output-low' property.
Yes, if the pin controller supports that. From Niklaus' emails, I was
under the impression it doesn't.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
