From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 90DCC4756A6; Fri, 7 Aug 2026 15:04:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786115061; cv=none; b=nBdfCOcHKFuUIsh1sF7OPwgN5tKYWbxxqZ5do1ePfW80t6FrDQ2yvtCz0FIgBtmfL8XKeRxcy/yv2LLjMvWP4hlzVbASNv6LpdpTGY05iNecJVoVfnLTLAOf/hziI4Bdp/ghRWesJF1mq3bqNJCd0ALDCaYzyYkecpJhx9I2u0M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786115061; c=relaxed/simple; bh=NdXj7gmagZgpRZrsZN0cZwyEa9+sKf/EUKHRnU7bD2Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=qRK7ntyz9/HewbQVguT+3WpQNOckdnBjZNG68Rsq2Avr50JHXHEjI3vMG8l4tRJgl0agHv92zls+XxGnX0Q/j4khmG+MpXIXhAUbda73EDmIFxSJu2Dc27s89gyVRdSLMPHIb88OVQB7LEnk5000SRwRPaOuKfXzKhiVoty8RNg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eav8DqaO; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eav8DqaO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 798591F00A3A; Fri, 7 Aug 2026 15:04:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786115048; bh=X2bYcZxMklD9Q06ufgES+elHsVF90macP4DQ1aKk8Pg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=eav8DqaOHqzxt9uUSAjGEm8VxTiQgE2dkaQKgFe3PtYUFG4NSy1i0wTCs+KsWppbQ ouQBKn1lmkEX2g4ioAPmbnTp5JJqW6OWrvzMhD6gYIIGt6tAH+AN4RxYLcWivhWI1f jt4lNqcTSBoV/yYqNgcaNc0vv2GvvVk8n6K4vxb8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ankit Nautiyal , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Alexander Kaplan , Rodrigo Vivi , Sasha Levin Subject: [PATCH 6.18 137/396] drm/i915/dp: Ignore the sinks DSC max FRL rate without a PCON DSC encoder Date: Fri, 7 Aug 2026 16:34:57 +0200 Message-ID: <20260807143427.264242706@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143424.272339768@linuxfoundation.org> References: <20260807143424.272339768@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexander Kaplan [ Upstream commit 8891e39e89042e285fd82fdde325d1311ec750a1 ] intel_dp_hdmi_sink_max_frl() limits the sink's max FRL rate by its DSC max FRL rate whenever the sink supports DSC 1.2. However, the DSC max FRL rate (HF-VSDB DSC_Max_FRL_Rate) only applies to compressed video transport, which requires a DSC 1.2 encoder in the PCON (configured via intel_dp_pcon_dsc_configure()). Without such an encoder the HDMI link always carries uncompressed video, for which the regular Max_FRL_Rate is the correct limit. Applying the DSC limit unconditionally trains the FRL link at a lower rate than both the PCON and the sink support. E.g. an LG OLED G4 (Max_FRL_Rate 48 Gbps, DSC_Max_FRL_Rate 24 Gbps) behind a Synaptics VMM7100 PCON (PCON max FRL bw 48 Gbps, no DSC encoder): Sink max rate from EDID = 24 Gbps FRL trained with : 24 Gbps while Windows/macOS train the same hardware at 40/48 Gbps. The too low FRL rate needlessly constrains the formats available to the sink. Only apply the sink's DSC max FRL rate if the PCON has a DSC 1.2 encoder, matching the gate in intel_dp_pcon_dsc_configure(). PCONs with a DSC encoder keep the current conservative behavior, since the link is trained once and compressed transport may be used for any subsequent mode. With this the setup above trains at 48 Gbps. Tested on PTL (xe) with the above PCON/sink combo. Fixes: 10fec80b48c5 ("drm/i915/display: Configure PCON for DSC1.1 to DSC1.2 encoding") Cc: Ankit Nautiyal Cc: Ville Syrjälä Reviewed-by: Ankit Nautiyal Signed-off-by: Alexander Kaplan Signed-off-by: Ankit Nautiyal Link: https://patch.msgid.link/20260718105207.5565-3-alexander.kaplan@sms-medipool.de (cherry picked from commit 71b57dd92f94569dca4bdf883fbd8ca5d4ed4bae) Signed-off-by: Rodrigo Vivi Signed-off-by: Sasha Levin --- drivers/gpu/drm/i915/display/intel_dp.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 2a0750acf2053..84fca860c93ee 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -3859,7 +3859,14 @@ static int intel_dp_hdmi_sink_max_frl(struct intel_dp *intel_dp) rate_per_lane = info->hdmi.max_frl_rate_per_lane; max_frl_rate = max_lanes * rate_per_lane; - if (info->hdmi.dsc_cap.v_1p2) { + /* + * The sink's DSC max FRL rate only applies to compressed video + * transport, which requires a DSC 1.2 encoder in the PCON. Without + * one the HDMI link always carries uncompressed video, for which + * the regular max FRL rate is the limit. + */ + if (drm_dp_pcon_enc_is_dsc_1_2(intel_dp->pcon_dsc_dpcd) && + info->hdmi.dsc_cap.v_1p2) { max_dsc_lanes = info->hdmi.dsc_cap.max_lanes; dsc_rate_per_lane = info->hdmi.dsc_cap.max_frl_rate_per_lane; if (max_dsc_lanes && dsc_rate_per_lane) -- 2.53.0