[Letux-kernel] [PATCH v8 6/8] MIPS: DTS: CI20: Add DT nodes for HDMI setup

H. Nikolaus Schaller hns at goldelico.com
Wed Nov 24 17:30:05 CET 2021


Hi Geert,

> Am 24.11.2021 um 17:21 schrieb Geert Uytterhoeven <geert at linux-m68k.org>:
> 
> Hi Nikolaus,
> 
> On Wed, Nov 24, 2021 at 5:19 PM H. Nikolaus Schaller <hns at goldelico.com> wrote:
>>> Am 23.11.2021 um 21:10 schrieb Paul Cercueil <paul at crapouillou.net>:
>>> Le mar., nov. 23 2021 at 19:13:59 +0100, H. Nikolaus Schaller <hns at goldelico.com> 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.
The driver assumes it can use pinmux state switching to drive the DDC_SDA line low on demand.

Since it is unlikely that we need it at all (and we have no test case that it works) I think we simply can leave
this driver feature unused unless we get a test case.

BR and thanks,
Nikolaus



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