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 42989285060; Mon, 9 Feb 2026 14:33:13 +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=1770647593; cv=none; b=YIFvztWc9PD+AbV2VTo7M7WSu6WN/sJYLZIj374eRgS37ZUJrehlKxw5hHimDPI5jqGTcShOk4dbqyTEYq8yexfOSMl8h5Stj+mFLTUmigIAA+XLAnsKcyZ01G8QBuz7IdsO5CWtAOJFFlPOOPsTtROMKfgkhX1fsWATS2hEs7I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770647593; c=relaxed/simple; bh=NZmr/9qI4fD1TMr9R3rjqnmxjQuRF25GoYuKqmxlYV4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=omXjl8hlcliHDp0O+oq9SZ5a3ZU9FpQi5jDPp2AtBhmtI0DecApihFOCFLZ1kjuMTnq9Tr8fCKv9MYZZp3j1g9lJnUpdr4I+j1mDATORJMrcp2I88mGOhF7Cj1N5p4Pt4nUTXfSoKhLXoydz7XZF0+JB8w3wVYlHuCgzufS0ax8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AXYuJ2UX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AXYuJ2UX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCA6CC116C6; Mon, 9 Feb 2026 14:33:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1770647593; bh=NZmr/9qI4fD1TMr9R3rjqnmxjQuRF25GoYuKqmxlYV4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AXYuJ2UXo1H4w+hwySshmPHX/xUNK2YNh7vL2M3ClyRd1IkH1ncDHrHA4e9fvQAWt yag/ds4XRxAgH2bk51d8Km7N+Qie2R1nE7z7pztGasG7cKXjsbcdWHagTxDle26GdW s6pS4rOwNMLfBdXMjCB7Vdy/b5ePy/C6woeAGymE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Krunoslav Kovac , Melissa Wen , Alex Hung , Alex Deucher , Sasha Levin Subject: [PATCH 6.18 146/175] drm/amd/display: fix wrong color value mapping on MCM shaper LUT Date: Mon, 9 Feb 2026 15:23:39 +0100 Message-ID: <20260209142325.756539270@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260209142320.474120190@linuxfoundation.org> References: <20260209142320.474120190@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Melissa Wen [ Upstream commit 8f959d37c1f2efec6dac55915ee82302e98101fb ] Some shimmer/colorful points appears when using the steamOS color pipeline for HDR on gaming with DCN32. These points look like black values being wrongly mapped to red/blue/green values. It was caused because the number of hw points in regular LUTs and in a shaper LUT was treated as the same. DCN3+ regular LUTs have 257 bases and implicit deltas (i.e. HW calculates them), but shaper LUT is a special case: it has 256 bases and 256 deltas, as in DCN1-2 regular LUTs, and outputs 14-bit values. Fix that by setting by decreasing in 1 the number of HW points computed in the LUT segmentation so that shaper LUT (i.e. fixpoint == true) keeps the same DCN10 CM logic and regular LUTs go with `hw_points + 1`. CC: Krunoslav Kovac Fixes: 4d5fd3d08ea9 ("drm/amd/display: PQ tail accuracy") Signed-off-by: Melissa Wen Reviewed-by: Alex Hung Signed-off-by: Alex Deucher (cherry picked from commit 5006505b19a2119e71c008044d59f6d753c858b9) Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c index 0690c346f2c52..a4f14b16564c2 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c +++ b/drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c @@ -163,6 +163,11 @@ bool cm3_helper_translate_curve_to_hw_format( hw_points += (1 << seg_distr[k]); } + // DCN3+ have 257 pts in lieu of no separate slope registers + // Prior HW had 256 base+slope pairs + // Shaper LUT (i.e. fixpoint == true) is still 256 bases and 256 deltas + hw_points = fixpoint ? (hw_points - 1) : hw_points; + j = 0; for (k = 0; k < (region_end - region_start); k++) { increment = NUMBER_SW_SEGMENTS / (1 << seg_distr[k]); @@ -223,8 +228,6 @@ bool cm3_helper_translate_curve_to_hw_format( corner_points[1].green.slope = dc_fixpt_zero; corner_points[1].blue.slope = dc_fixpt_zero; - // DCN3+ have 257 pts in lieu of no separate slope registers - // Prior HW had 256 base+slope pairs lut_params->hw_points_num = hw_points + 1; k = 0; -- 2.51.0