From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 34E7D18DB1E for ; Fri, 5 Dec 2025 08:32:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764923536; cv=none; b=XvCpUTOZJVjHH0+K0NKQ93ZThB/HjCUqMtl7P7plslEYVzifV3IxhUUX2ttVpH+EdJccLgdlS4rwMFzZ3EXOgjGSSpDRWK+tDOXE7gZG91AQofhXbmCo48GM/Dnjwl5Qc80yG7m5a67HV87WdZiZc6Ahmsnj9WQR1A4td3N01XQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764923536; c=relaxed/simple; bh=c9amunadGf72qukjWj0Yig/o3zNWjowWuABEzR+a5j4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FomcTnLREWWXd59S1E3fsC98XGcp00uHqxqiKZENLvrzCPkAnl70jEs6rdmcnmWBVHU2jmIH/rSz9v12rs2JaIP8M3CXJ4npflPgX3fZ/lyMjNTTpqsM/KryKwgD1HjHO/LElCdGmroKVJTookL4jdlrKFIkRvb9EjWLx7/cYXM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EpHlSGrK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EpHlSGrK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26500C4CEF1; Fri, 5 Dec 2025 08:32:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764923534; bh=c9amunadGf72qukjWj0Yig/o3zNWjowWuABEzR+a5j4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EpHlSGrKOs4sy2BLfgCYjpWCTF/aVgPpxmhRbSksP5gOYxTYuCGkmCSaP5zAYIOEl mtan7naNzAKDlhBNBPqtkADJHTnn8kdiwaxA1CQ25ySCrcHrrEmL57bGO0YIdmhpBC OmmOzqxhd4Mv6PYp8Lgjb64lWhBWX3AAhTjjM1VVuHelGXAIQuDxt6gcF687jmuuCo UOHbu4dvnrwMkC++mxqd4WOzq4HAdCP1rEEyVU10mNCaYRuRX8LjIXvmNI3bHDwPfA F0/PfQGSSLvJVEy1nvghXFi5uxc/Mp5q5PryzKxC2mbBhRwMjmIFCMALvTKpi5snOH RSvh9o+ZUusRg== Date: Fri, 5 Dec 2025 09:32:11 +0100 From: Maxime Ripard To: Laurent Pinchart Cc: Tomi Valkeinen , Linus Walleij , Marek Vasut , Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , Tomi Valkeinen , Kieran Bingham , Geert Uytterhoeven , Magnus Damm , Aradhya Bhatia , Dmitry Baryshkov , dri-devel@lists.freedesktop.org, linux-renesas-soc@vger.kernel.org, Geert Uytterhoeven , Vicente Bergas Subject: Re: [PATCH v5 0/3] drm/atomic-helpers: Fix MCDE/R-Car DU regressions Message-ID: <20251205-magnificent-mink-of-completion-acef96@houat> References: <20251130-mcde-drm-regression-thirdfix-v5-0-aed71a32981d@kernel.org> <20251202063403.GA18267@pendragon.ideasonboard.com> <20251203022229.GJ8219@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-renesas-soc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha384; protocol="application/pgp-signature"; boundary="w426pplwbuemy3ay" Content-Disposition: inline In-Reply-To: <20251203022229.GJ8219@pendragon.ideasonboard.com> --w426pplwbuemy3ay Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v5 0/3] drm/atomic-helpers: Fix MCDE/R-Car DU regressions MIME-Version: 1.0 On Wed, Dec 03, 2025 at 11:22:29AM +0900, Laurent Pinchart wrote: > On Tue, Dec 02, 2025 at 10:58:50AM +0200, Tomi Valkeinen wrote: > > On 02/12/2025 08:34, Laurent Pinchart wrote: > > > On Sun, Nov 30, 2025 at 01:11:16PM +0100, Linus Walleij wrote: > > >> This fixes two regressions experienced in the MCDE and > > >> R-Car DU DRM drivers after > > >> commit c9b1150a68d9362a0827609fc0dc1664c0d8bfe1 > > >> "drm/atomic-helper: Re-order bridge chain pre-enable and post-disabl= e" > > >> caused a series of regressions in all panels that send > > >> DSI commands in their .prepare() and .unprepare() > > >> callbacks. > > >> > > >> This series make it possible to selectively bring back the > > >> old behaviour with explicit semantics and implements > > >> the old behaviour as modified commit tails in MCDE and > > >> R-Car DU. > > >=20 > > > We now have a third platform broken by > > > c9b1150a68d9362a0827609fc0dc1664c0d8bfe1, see [1]. I think this calls > > > for a revert, to give us the time to implement a correct solution. > > > > Perhaps... It's been very slow or not possible to get feedback regarding > > (some) of the broken platforms, so I don't think we have a safe way of > > changing the enable/disable sequence. I think the "correct" solution > > then is to make this new enable/disable sequence either opt-in, offered > > by the framework, or just implement it as a custom sequence in the > > specific drm driver. >=20 > I don't think that's right, sorry. We need to improve the bridge API to > handle ordering properly. Changes to the commit tail handlers in display > controller drivers are hacks, they handle issues with the internal DSI > transmitters, but if you had a LVDS-to-DSI bridge in the pipeline things > would still break. >=20 > > Reverting c9b1150a68d9362a0827609fc0dc1664c0d8bfe1 will break DSI and > > OLDI outputs on TI platforms, so we need to implement a fix for those > > platforms before the revert, and there has been one or two fixes merged > > for other platforms for this, which most likely also need to get revert= ed. >=20 > That's 3 vs. 1, so I think breaking DSI and OLDI with a revert is better > than not reverting the commit. If we can merge a propert solution at the > same time that's great, but the first target is to restore operation of > the drivers that got broken. Yeah, I agree. Could it be possible to flip the custom commit_tail implementation and instead implement it into tidss while the core changes are reverted to avoid the regressions and keeping tidss functional? Maxime --w426pplwbuemy3ay Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJUEABMJAB0WIQTkHFbLp4ejekA/qfgnX84Zoj2+dgUCaTKYhgAKCRAnX84Zoj2+ dm96AX9aFdLXVXxx6yJeAgbJvUYIUixO+lAuqMiQIJaRe59pt+BtEkeSLFw+SIuF V7xf1BsBgPKNQ8TCge5gTH8thJ9iYxW+yrkQuIQWRs8cmIYJIC59Aue+lVXKhO22 wwTEoUkXUQ== =NKno -----END PGP SIGNATURE----- --w426pplwbuemy3ay--