linux-kernel - Re: [PATCH 0/4] drm: Revert and fix enable/disable sequence

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Message-ID: <b2f3e15c-1a15-427d-90d9-ea0e33b50ecb@samsung.com>
Date: Fri, 5 Dec 2025 15:25:52 +0100
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>, Andrzej Hajda <andrzej.hajda@...el.com>,
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman
	<jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, Dmitry
	Baryshkov <lumag@...nel.org>, Chun-Kuang Hu <chunkuang.hu@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>, Matthias Brugger
	<matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>, Jyri Sarha <jyri.sarha@....fi>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	linux-mediatek@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
	Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>, Aradhya Bhatia
	<aradhya.bhatia@...ux.dev>, Linus Walleij <linusw@...nel.org>, Chaoyi Chen
	<chaoyi.chen@...k-chips.com>, Vicente Bergas <vicencb@...il.com>, Marek
	Vasut <marek.vasut+renesas@...lbox.org>, stable@...r.kernel.org
Subject: Re: [PATCH 0/4] drm: Revert and fix enable/disable sequence

On 05.12.2025 10:51, Tomi Valkeinen wrote:
> Changing the enable/disable sequence in commit c9b1150a68d9
> ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable")
> has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
>
> This is an alternate series to Linus' series:
>
> https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bffd4ec0fa%40kernel.org/
>
> This series first reverts the original commit and reverts a fix for
> mediatek which is no longer needed. It then exposes helper functions
> from DRM core, and finally implements the new sequence only in the tidss
> driver.
>
> There is one more fix in upstream for the original commit, commit
> 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with
> runtime PM calls"), but I have not reverted that one as it looks like a
> valid patch in its own.

Right, that patch is a fix on its own, the changes in the atomic 
sequence just revealed the issue.

> I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as
> I wasn't sure what should they point to. But I could perhaps add Fixes:
> <original commit> to all of these.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> ---
> Linus Walleij (1):
>        drm/atomic-helper: Export and namespace some functions
>
> Tomi Valkeinen (3):
>        Revert "drm/atomic-helper: Re-order bridge chain pre-enable and post-disable"
>        Revert "drm/mediatek: dsi: Fix DSI host and panel bridge pre-enable order"
>        drm/tidss: Fix enable/disable order
>
>   drivers/gpu/drm/drm_atomic_helper.c | 122 ++++++++++++++----
>   drivers/gpu/drm/mediatek/mtk_dsi.c  |   6 -
>   drivers/gpu/drm/tidss/tidss_kms.c   |  30 ++++-
>   include/drm/drm_atomic_helper.h     |  22 ++++
>   include/drm/drm_bridge.h            | 249 ++++++++++--------------------------
>   5 files changed, 214 insertions(+), 215 deletions(-)
> ---
> base-commit: 88e721ab978a86426aa08da520de77430fa7bb84
> change-id: 20251205-drm-seq-fix-b4ed1f56604b

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland