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Mon, 24 Aug 2026 06:15:47 -0700 (PDT) X-Received: by 2002:a05:6102:d8e:b0:778:1bcd:ddc0 with SMTP id ada2fe7eead31-77a5f8ee1f7mr3817872137.0.1787577347380; Mon, 24 Aug 2026 06:15:47 -0700 (PDT) Received: from [192.168.120.193] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5b48cda2b20sm1739539e87.25.2026.08.24.06.15.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Aug 2026 06:15:46 -0700 (PDT) Message-ID: <315db50d-6553-412d-8fca-a4b4441f881b@oss.qualcomm.com> Date: Mon, 24 Aug 2026 15:15:43 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/4] drm/msm/dp: skip LTTPR init when no LTTPRs are present To: Saurabh Anand , Vinod Koul , Neil Armstrong , Manivannan Sadhasivam , Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Jessica Zhang , Sean Paul , Marijn Suijten , David Airlie , Simona Vetter Cc: linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, Ritesh Kumar , Vishnuvardhan Prodduturi , Mani Chandana Kuntumalla , Mahadevan P References: <20260824-qcom-dp-typec-reconnect-fixes-v1-0-2825e5bf8a96@oss.qualcomm.com> <20260824-qcom-dp-typec-reconnect-fixes-v1-3-2825e5bf8a96@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260824-qcom-dp-typec-reconnect-fixes-v1-3-2825e5bf8a96@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI0MDExMSBTYWx0ZWRfX2PYlt2GE3gU5 ekh/4M7aFOb2NU8lxOzqJn4ZTWCgdmRRtcAtNcuJYOI4WKgHlnWQWUZRUJGRGgnXq6k5HlmkrtN a8zy8ONhAMXOY27JxNWyx2ZVBHx8t3pQh7wVtVV5lGPK3NbkZByaHyW9d/G5/Zbq8KGCCZRLWZ0 WlZ1S7rnsh4fm2vwy4s0crO8BQ5N40Eff90gizrfWwuM+hZHTVt7tHM2e2QoEKonLwxVULjoKzc gJYnopNeHudwwhm1nM0Y8WgBpXNUhrMwAsamkQh834kgGowqeka2pj53j3AqPK89h2GVLPpkwdL EodiOD0gawNeGjuWVwmiEH5ocSDigiW2ooC2nmUMScOXdMSGfP5hc/yMC6QPvCRXnK0Ger8UKuc XzA84aWJRAaOdDrFFqS6WIkF/HVl4L33rBW3/sTj1a4sxSJywvZ4fid39biOeVMLzRkdx5xx2WD MmCzMlwcD1Nd8i6JC1g== X-Authority-Analysis: v=2.4 cv=JL0LdcKb c=1 sm=1 tr=0 ts=6a8c4404 cx=c_pps a=DUEm7b3gzWu7BqY5nP7+9g==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_K5XuSEh1TEqbUxoQ0s3:22 a=HlmmvPtyU3BZVRE9FHQA:9 a=QEXdDO2ut3YA:10 a=zgiPjhLxNE0A:10 a=-aSRE8QhW-JAV6biHavz:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI0MDExMSBTYWx0ZWRfX4mQw6MXua+0m 0wBjsCMtw2QuhOZANFUCeCMZNAeAU8pYd/Gb1u3c0/F1Fm46eoRZ2lVlr6PQO3/v/MYUHRkuf71 Rm9ZALZwqWol+MJRzvurwY7q0zTRYmI= X-Proofpoint-GUID: mJCYZmWUD8YanB0PNq1ISlOrVjEo7Nej X-Proofpoint-ORIG-GUID: mJCYZmWUD8YanB0PNq1ISlOrVjEo7Nej X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-24_04,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 suspectscore=0 clxscore=1015 impostorscore=0 priorityscore=1501 adultscore=0 bulkscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608240111 On 8/24/26 1:28 PM, Saurabh Anand wrote: > drm_dp_lttpr_count() returns 0 when no LTTPRs are detected and a > negative value on error. The previous code passed the result directly > to drm_dp_lttpr_init() without checking, which would call into the > LTTPR transparency-mode setup with a zero or negative repeater count. > > Add an early return for lttpr_count <= 0 to skip the init entirely > when there are no repeaters in the link, matching the expected usage > of drm_dp_lttpr_init(). Reading the body of that function, I'm not sure your statement is true Konrad