Hi Paul,

On Thu, Nov 25, 2021 at 10:02 AM Paul Cercueil [off-list ref] wrote:

Le jeu., nov. 25 2021 at 08:58:13 +0100, Geert Uytterhoeven
[off-list ref] a écrit :

quoted

On Wed, Nov 24, 2021 at 5:31 PM H. Nikolaus Schaller
[off-list ref] wrote:

quoted

 > Am 24.11.2021 um 17:21 schrieb Geert Uytterhoeven
[off-list ref]:
 > On Wed, Nov 24, 2021 at 5:19 PM H. Nikolaus Schaller
[off-list ref] wrote:
 >>> Am 23.11.2021 um 21:10 schrieb Paul Cercueil
[off-list ref]:
 >>> Le mar., nov. 23 2021 at 19:13:59 +0100, H. Nikolaus Schaller
[off-list ref] 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).

quoted

 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@linux-m68k.org

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