From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from n169-113.mail.139.com (n169-113.mail.139.com [120.232.169.113]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 552E2285CAE for ; Tue, 30 Jun 2026 15:03:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=120.232.169.113 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782831829; cv=none; b=GqVrw9dbZ+1z/dV9ehlkbpuvUZ84130vO5uE+tSjWslcENlSricN3CzRXbc5sSTsti28F/x+QnC8wTjK+ahJYP9Ii42rJFH7zAmlAkmwC0ysjnwC2F9wHr/Y+aX7yAxdketm5wLHOqI2hXlvVmGN8B0xxRAEHv87nNKvfUQOX8s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782831829; c=relaxed/simple; bh=6lVNmfB0Kkge6B3j8BQG5xuMlO6MbOWKJXHqKYMqCeI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=qe3AUUdorJCZFAF0aIZlk+FoxTxg0ILGcv0Uh4ldDwbyw1+vxXFkFnGtPdiykw1H1GoR8Lcz4JnnuRYNHw82u6dZWf0hh78YwYrPQ0lHeUJ7h4QyPFlq40fvKS/9X55RtXyW/iYdr73kkDDNb2geHFoInBnLgYeIICeGP1SbKbg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=139.com; spf=pass smtp.mailfrom=139.com; dkim=pass (1024-bit key) header.d=139.com header.i=@139.com header.b=VIcaokEu; arc=none smtp.client-ip=120.232.169.113 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=139.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=139.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=139.com header.i=@139.com header.b="VIcaokEu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=139.com; s=dkim; l=0; h=from:subject:message-id:to:cc:mime-version; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; b=VIcaokEuiOIFYvtdM48QKVnsxwG2kkrmSLbyDxYqtAGXRcYVFgbt30lU1YJ37wO9T86QTK2lae+uA lJares/U6mm3pae0kau4OqH7BRnBt3voSE8so0jC1LQF9Mf/dirufMdgji2tfCnN4Y4SD2SazAllpF ByPYHPn6/5XytH1w= X-RM-TagInfo: emlType=0 X-RM-SPAM: X-RM-SPAM-FLAG:00000000 Received:from yoga-Yoga-Pro-7-15ASH11.. (unknown[2409:8A00:7882:4A80:26A:22CB:C855:10DC]) by rmsmtp-lg-appmail-34-12048 (RichMail) with SMTP id 2f106a43d9f90a9-020d0; Tue, 30 Jun 2026 23:00:22 +0800 (CST) X-RM-TRANSID:2f106a43d9f90a9-020d0 From: Jackie Dong To: harry.wentland@amd.com, sunpeng.li@amd.com, siqueira@igalia.com, alexander.deucher@amd.com, christian.koenig@amd.com, airlied@gmail.com, simona@ffwll.ch, alex.hung@amd.com, ivan.lipski@amd.com, wenjing.liu@amd.com, robin.chen@amd.com, superm1@kernel.org, meenakshikumar.somasundaram@amd.com, Derek.Lai@amd.com, wei-guang.li@amd.com, gaghik.khachatrian@amd.com, jack.chang@amd.com, Duncan.Ma@amd.com, PeiChen.Huang@amd.com, aurabindo.pillai@amd.com, zhao.xichao@vivo.com Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Jackie Dong Subject: [PATCH] drm/amd/display:Check dp_128b_132b_supported_link_rates.raw before link_rate setting Date: Tue, 30 Jun 2026 22:59:55 +0800 Message-ID: <20260630145955.13994-1-xy-jackie@139.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit [WHY] In the evolution of displays from DP 1.4 to DP 2.0, due to considerations some factors,such as cost, some displays support 128b/132b encoding but do not support UHBR rate transmission. The values can be read from DPCD register address as below. 0x00006 is 03 0x02215 is 00 For such displays, the current kernel reports the following error message. [drm:dp_retrieve_lttpr_cap [amdgpu]] *ERROR* retrieve_link_cap: Invalid RX 128b_132b_supported_link_rates [HOW] Add new judgment: if all bits in dp_128b_132b_supported_link_rates.raw are non-zero, then further determine the specific UHBR type; otherwise, determine that the display does not support UHBR. Signed-off-by: Jackie Dong --- .../gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c index 47abb4066709..58cbb7ac8f9e 100644 --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c @@ -2079,7 +2079,8 @@ static bool retrieve_link_cap(struct dc_link *link) if (!dpcd_read_sink_ext_caps(link)) link->dpcd_sink_ext_caps.raw = 0; - if (link->dpcd_caps.channel_coding_cap.bits.DP_128b_132b_SUPPORTED) { + if (link->dpcd_caps.channel_coding_cap.bits.DP_128b_132b_SUPPORTED && + link->dpcd_caps.dp_128b_132b_supported_link_rates.raw) { DC_LOG_DP2("128b/132b encoding is supported at link %d", link->link_index); /* Read 128b/132b suppoerted link rates */ -- 2.43.0