linux-kernel - Re: [PATCH v2 2/8] drm/ssd130x: Fix screen clearing

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Date:   Tue, 29 Aug 2023 10:40:59 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH v2 2/8] drm/ssd130x: Fix screen clearing

Geert Uytterhoeven <geert@...ux-m68k.org> writes:

Hello Geert,

Thanks a lot for your patch.

> Due to the reuse of buffers, ssd130x_clear_screen() no longers clears
> the screen, but merely redraws the last image that is residing in the
> intermediate buffer.
>
> As there is no point in clearing the intermediate buffer and transposing
> an all-black image, fix this by just clearing the HW format buffer, and
> writing it to the panel.
>
> Fixes: 49d7d581ceaf4cf8 ("drm/ssd130x: Don't allocate buffers on each plane update")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
> ssd130x_clear_screen() is only called from
> ssd130x_primary_plane_helper_atomic_disable(), but this never happens on
> my system.
>

AFAIU this should be called if the outputs get disabled.

> Tested by adding some extra calls to ssd130x_clear_screen() at regular
> intervals.
>
> v2:
>   - New.
> ---
>  drivers/gpu/drm/solomon/ssd130x.c | 47 +++++++++++++++++++++++++------
>  1 file changed, 39 insertions(+), 8 deletions(-)
>

The change makes sense to me.

Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat