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From:   Javier Martinez Canillas <javierm@redhat.com>
To:     Thomas Zimmermann <tzimmermann@suse.de>,
        linux-kernel@vger.kernel.org
Cc:     Maxime Ripard <mripard@kernel.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@gmail.com>,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v4] drm/ssd130x: Allocate buffers in the plane's
 .atomic_check callback
In-Reply-To: <76cea601-2730-21a7-f52b-1d53be343d6e@suse.de>
References: <20230721070955.1170974-1-javierm@redhat.com>
 <76cea601-2730-21a7-f52b-1d53be343d6e@suse.de>
Date:   Thu, 27 Jul 2023 15:43:44 +0200
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Thomas Zimmermann <tzimmermann@suse.de> writes:

Hello Thomas,

Thanks a lot for the feedback!

> Hi Javier,
>
> this patch is completely broken. It's easy to fix though.
>
> Am 21.07.23 um 09:09 schrieb Javier Martinez Canillas:

[...]

>> +struct ssd130x_plane_state {
>> +	struct drm_plane_state base;
>
> You need to use a struct drm_shadow_plane_state here.
>

Yes, I already noticed this when testing Arnd's patch to drop
DRM_GEM_SHADOW_PLANE_FUNCS. I already have a patch ready.

[...]

+
>>   static const struct drm_plane_helper_funcs ssd130x_primary_plane_helper_funcs = {
>>   	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
>
> This macro sets the callbacks that vmap/vunmap the GEM buffer during the 
> display update. They expect to upcast from drm_plane_state to 
> drm_shadow_plane_state.  And hence, your driver's plane state needs to 
> inherit from drm_shadow_plane_state.
>

Yup. I missed that. I'm now testing my patch and will post it.

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat