From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 3DF2234676F for ; Fri, 6 Feb 2026 09:09:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770368949; cv=none; b=bALz5G9glVVV3DO5VlUiKcCFCf+7jA4m2KHenExSEqTWZwu5F3KfjidQ+7WmK3dPA2uCEGojKZ7e0YZ656i/vc7g+q4BOtP/43CNA0yvGsBY9+y2VWYt/wcBXSxM2lTr33W27JrrMO1Q+RlFcMhp2OyRJ0AAYdTEig+rvTjxhzc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770368949; c=relaxed/simple; bh=81Nfnr+VgGFh1r1KxdRZ/fW91tng+mO/I9oWaPLw1M8=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lcm+aZ4EMJpTLdKctDUFKuonMsnQ57/7TSmNvPR9Zh/XO/Iv65V3333cP29KwCuwdKwjuNJF+Ww32BsccOhfCwjB0ltwlLngMpCbPv8Zd/0+oF/ujdmh1sJs+CR/ekUCaMUHzqhm/aq816n10ov4s3ccfJX0GlO2RGPdomhdTQk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=Zeq14iJA; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="Zeq14iJA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1770368947; bh=81Nfnr+VgGFh1r1KxdRZ/fW91tng+mO/I9oWaPLw1M8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Zeq14iJASuWMiCVaPM0Pq1VwmwDFxdyiFG+ZAxgtEY75PnbG9du504E8hcTbBT7aR ERjhnQPjndIHwksoMMDmEVPT4xW0SG4yU7b9Kt2wML+uSK8XwTpJY7aGhnf1sYREb4 aDsdsN4D/aBFWNr3SY5PprTvRMKcznkaf6l/0g3muSFrXZ+KE6zHHYnFDChVkz8IWT kP8Udb2kwJm9E071SiJ9sA44iumwg8wIBoawYmxQpER9Y5fQ0COzRQWrFUYMw3iSjt UqkKrN0uGXhlsox06qmdQeKLADO8ehDkXDUOQXflk8w4xRcBdm+XjU7kGwMJkb6DbR YpdPjUXTBWUpg== Received: from eldfell (unknown [194.136.85.206]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: pq) by bali.collaboradmins.com (Postfix) with ESMTPSA id 837A117E1352; Fri, 6 Feb 2026 10:09:06 +0100 (CET) Date: Fri, 6 Feb 2026 11:09:01 +0200 From: Pekka Paalanen To: Harry Wentland Cc: Shengyu Qu , "=?UTF-8?B?TsOtY29sYXM=?= F. R. A. Prado" , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Chun-Kuang Hu , Philipp Zabel , Matthias Brugger , AngeloGioacchino Del Regno , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, daniels@collabora.com, ariel.dalessandro@collabora.com, kernel@collabora.com, xaver.hugl@gmail.com Subject: Re: [PATCH 00/11] Plane Color Pipeline support for MediaTek Message-ID: <20260206110901.660cf712@eldfell> In-Reply-To: References: <20251223-mtk-ovl-pre-blend-colorops-v1-0-0cb99bd0ab33@collabora.com> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="Sig_/hCOlWIbx7XSjDW26hBp0SP7"; protocol="application/pgp-signature"; micalg=pgp-sha256 --Sig_/hCOlWIbx7XSjDW26hBp0SP7 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Fri, 2 Jan 2026 13:40:21 -0500 Harry Wentland wrote: > On 2026-01-01 07:37, Shengyu Qu wrote: > >=20 > >=20 > > =E5=9C=A8 2025/12/30 02:53, Shengyu Qu =E5=86=99=E9=81=93: =20 > >> > >> > >> =E5=9C=A8 2025/12/24 3:44, N=C3=83 colas F. R. A. Prado =E5=86=99=E9= =81=93: =20 > >>> Given the lack of support for writeback connectors on the > >>> MediaTek KMS driver, combined with limited hardware > >>> documentation, I haven't been able to verify the correctness of > >>> each curve, only that they were visually sane (gamma curves made > >>> the image on the display brighter, while inverse gamma made it > >>> darker). =20 > >> > >> Hmmm I don't think this is acceptable. sRGB/scRGB has two transfer > >> functions mentioned in original specification[1]. To keep color > >> accuracy, we need someone from mediatek confirm whether this is > >> piece- wise or pure power 2.2 transfer function, this is already > >> done in original amdgpu color pipeline series, sRGB means > >> piece-wise while also dedicated power 2.2 function exists. =20 >=20 > Not sure what you mean with this not being acceptable. This is about > enabling HW support for this functionality. Not every HW has > writeback for testing. At some point you'll have to trust the driver > devs if you're going to use functionality of the driver. We're not > always going to get everything perfect, but if that's really such a > worry you can always use shaders to do precisely what you want. >=20 Hi Harry, yes, but I understood that in this case, the hardware documentation available is so vague that it's impossible to say what it will actually do. There are no formulas given or referenced in the documentation, are there, N=C3=ADcolas? The "HLG EOTF" is probably a good example of that, referring to the reply I just sent on the patch adding "HLG" as a curve. 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