linux-kernel - Re: [PATCH v2] drm/mediatek: Call drm_atomic_helper

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Message-ID: <CACRpkda4KbfWnMwFyJAFKeyvJ3A32D1WuEQd=VQpQcg02-+32Q@mail.gmail.com>
Date: Mon, 17 Jun 2024 11:04:21 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Douglas Anderson <dianders@...omium.org>
Cc: Chun-Kuang Hu <chunkuang.hu@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Fei Shao <fshao@...omium.org>, 
	Maxime Ripard <mripard@...nel.org>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, Daniel Vetter <daniel@...ll.ch>, 
	David Airlie <airlied@...il.com>, Matthias Brugger <matthias.bgg@...il.com>, 
	dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH v2] drm/mediatek: Call drm_atomic_helper_shutdown() at
 shutdown time

On Tue, Jun 11, 2024 at 7:28 PM Douglas Anderson <dianders@...omium.org> wrote:

> Based on grepping through the source code this driver appears to be
> missing a call to drm_atomic_helper_shutdown() at system shutdown
> time. Among other things, this means that if a panel is in use that it
> won't be cleanly powered off at system shutdown time.
>
> The fact that we should call drm_atomic_helper_shutdown() in the case
> of OS shutdown/restart comes straight out of the kernel doc "driver
> instance overview" in drm_drv.c.
>
> This driver users the component model and shutdown happens in the base
> driver. The "drvdata" for this driver will always be valid if
> shutdown() is called and as of commit 2a073968289d
> ("drm/atomic-helper: drm_atomic_helper_shutdown(NULL) should be a
> noop") we don't need to confirm that "drm" is non-NULL.
>
> Suggested-by: Maxime Ripard <mripard@...nel.org>
> Reviewed-by: Maxime Ripard <mripard@...nel.org>
> Reviewed-by: Fei Shao <fshao@...omium.org>
> Tested-by: Fei Shao <fshao@...omium.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij