Re: [PATCH v12 2/9] drm/ingenic: Add support for JZ4780 and HDMI output

[H. Nikolaus Schaller]

Hi Paul,

> Am 02.02.2022 um 13:06 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>:
> 
> Hi Nikolaus,
> 
>>>> @@ -446,6 +454,9 @@ static int ingenic_drm_plane_atomic_check(struct drm_plane *plane,
>>>> 	if (!crtc)
>>>> 		return 0;
>>>> +	if (plane == &priv->f0)
>>>> +		return -EINVAL;
>>> This will break JZ4725B -> JZ4770 SoCs, the f0 plane is perfectly usable there.
>> Hm. I think it was your request/proposal to add this [1]?
> 
> Because otherwise with your current patchset the f0 plane does not work *on JZ4780*.

Not that I am eager to fix that, but...
maybe it could be better to fix than having the check and -EINVAL depend on SoC compatible string
(or some new flag in soc_info. plane_f0_not_working)?

> It does work on older SoCs.
> 
>> What I have forgotten is why the f0 plane should not be usable for jz4780.
> 
> We return an error here to prevent userspace from using the f0 plane until it's effectively working on the JZ4780.

Well, what would be not working with that plane if user-space would try to use it?

> 
> Cheers,
> -Paul

BR and thanks,
Nikolaus