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smtp.subspace.kernel.org; dmarc=pass header.from=hsal.es; spf=pass smtp.mailfrom=hsal.es; dkim=pass header.d=hsal.es header.i=@hsal.es header.a=rsa-sha256 header.s=MBO0001 header.b=C8fdtVxC; arc=none smtp.remote-ip=80.241.56.171 Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [80.241.56.171]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C231960A380A for ; Fri, 13 Nov 2026 21:11:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org C231960A380A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=hsal.es Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=hsal.es Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=hsal.es header.i=@hsal.es header.a=rsa-sha256 header.s=MBO0001 header.b=C8fdtVxC Received: from smtp102.mailbox.org (smtp102.mailbox.org [IPv6:2001:67c:2050:b231:465::102]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519MLKEM768 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-201.mailbox.org (Postfix) with ESMTPS id 4jR9154rJSzMlfM; Fri, 13 Nov 2026 22:11:37 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hsal.es; s=MBO0001; t=1794604297; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=805vWcU4s6eOEpd5cH6cfQExyrCaLJl8qkBZOQ/FylY=; b=C8fdtVxCOdjrK4+sEfWY1pKjEhf/OEg8aYlUR6L1VkxbDEJibiZQkf26eSchpT2lbCDyZz 0r3sPsDXtyoKn13uZkC7uh3ljQ0nCZD6oh8FfFCPcWjKfkiZou/Tia1W2630Rf0AFb0BQc p0pYv6vymP2YNhqyTeuYRNNukBxnA5BnVcbayQo2Pf977pZZ4Rt0XSwEZRkSLhp2H1Fnty 9AFCtSLJWlhXWLm6U/GtTe4IPTYQ+Xy6UVqkhwDSspwdfTrlfccxI5hpeqmBWhDm5NkAf0 yBxL6qit26QarX1zgvJr0o2jdhVhDYvaluOkjdaKffZv/ccdvlaVu21TJNQlYg== Authentication-Results: outgoing_mbo_mout; dkim=none; spf=pass (outgoing_mbo_mout: domain of hugo@hsal.es designates 2001:67c:2050:b231:465::102 as permitted sender) smtp.mailfrom=hugo@hsal.es Date: Fri, 13 Nov 2026 21:11:36 +0000 (WET) From: Hugo Sales To: Ray Wu , alexander.deucher@amd.com, sunpeng.li@amd.com, harry.wentland@amd.com, siqueira@igalia.com, amd-gfx@lists.freedesktop.org Cc: simona@ffwll.ch, alex.hung@amd.com, mario.limonciello@amd.com, linux-kernel@vger.kernel.org, lohita.mudimela@amd.com, bhawanpreet.lakha@amd.com, dri-devel@lists.freedesktop.org, roman.li@amd.com, airlied@gmail.com, christian.koenig@amd.com Message-ID: <1406290810.470231.1794604296696@app.mailbox.org> In-Reply-To: <7099a8ba-6508-4771-a97f-c681d0a8ceae@amd.com> References: <20261103-backlight-curve-rfc-v1-0-6e4813a8f2eb@hsal.es> <7099a8ba-6508-4771-a97f-c681d0a8ceae@amd.com> Subject: Re: [PATCH RFC RFT 0/8] drm/amd/display: Stop rounding backlight levels to whole percents X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Priority: 3 Importance: Normal X-Mailer: Open-Xchange Mailer v8.53.348 X-Originating-Client: open-xchange-appsuite X-Rspamd-Queue-Id: 4jR9154rJSzMlfM On 11/11/2026 9:22 AM WET Ray Wu wrote: > Patches 2/8 and 3/8 (LUT interpolation in the power module) are still > useful on top of it, and I have already given my Reviewed-by on those. > > Could you test it on your machine? Hi Ray, Thanks, and sorry for the delay. I tested your four patches with 2/8 and 3/8 on top, on an ASUS ROG Flow X13 GV301QH, a Cezanne laptop with a PWM backlight. I have no AUX panel, so this only covers the PWM path With ABM off, I wrote these levels to brightness and read actual_brightness back: level actual PWM 1 1 0x0004 500 500 0x055d 1000 1000 0x0ab9 2000 1999 0x0f1c 32768 32769 0x6263 65534 65534 0xfffd >From 0 to 3000 in steps of 50, the 61 levels got 61 different PWM values. Across the whole range, in steps of 1024, the PWM never went down. With your patches alone, 1 to 655 read back as 0, 1000 as 655 and 65534 as 64880 v1's 4/8 still matters for released kernels. Since commit 3c108046e1d6 ("drm/amd/display: Add power module on Linux") in 7.2, amdgpu_dm hands the power module whole percents, so PWM panels get at most 101 levels. Before it, amdgpu_dm passed a 16-bit PWM value straight to dc_link_set_backlight_level(). Your series alone still rounds to whole percents too, in the power module's LUT, so the rounding needs fixing either way. Which would you prefer: - I send a v2 now that fixes it on the current tree: 4/8 with a Fixes tag, plus 2/8, 3/8 and their tests, on top of "drm/amd/display: Fix the doubled AUX backlight minimum on the custom curve" [1]. Your series then replaces the amdgpu_dm part - I wait for your series and fix it on top of that. Your series already removes the rounding in amdgpu_dm, so that only needs 2/8 and 3/8 Thanks, Hugo [1] https://lore.kernel.org/r/20261103-amdgpu-aux-curve-min-v1-0-62119efdcc6d@hsal.es