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[2001:14ba:a073:af00:264b:feff:fe8b:be8a]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a3eee86784sm174147e87.8.2026.04.09.14.36.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Apr 2026 14:36:12 -0700 (PDT) Date: Fri, 10 Apr 2026 00:36:09 +0300 From: Dmitry Baryshkov To: Ville =?utf-8?B?U3lyasOkbMOk?= Cc: Kory Maincent , Jani Nikula , Rodrigo Vivi , Joonas Lahtinen , Tvrtko Ursulin , David Airlie , Simona Vetter , Dave Airlie , Jesse Barnes , Eric Anholt , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Chun-Kuang Hu , Philipp Zabel , Matthias Brugger , AngeloGioacchino Del Regno , Chris Wilson , Thomas Petazzoni , Mark Yacoub , Sean Paul , Louis Chauvet , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Simona Vetter Subject: Re: [PATCH RFC 00/12] Add support for DisplayPort link training information report Message-ID: References: <20260409-feat_link_cap-v1-0-7069e8199ce2@bootlin.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: X-Proofpoint-ORIG-GUID: Y9c9hjHUAoliZhjywkcp32oqouT6tEYE X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDA5MDE5OSBTYWx0ZWRfX4Gr71BlF8rZ2 6TauWY6QGpbxA6XOC8yxg8Y5/0ysOw7jL2QXaNUL/qvPppDAaLcV7nLqIFG6o/m1AstBwWQflyz 5c7rME9peh7yepxL36PpIaSvllHMKN5BKdoq3ILl7NI98jGgG76B7s4IwGa7EIJifsr5+KvjucX WujxsmCr41AOz879LqPMx52/YiI95uDX5GsijzlGX9VRB08czW5SssqlEFG0asQj7WZ6vCUANnN g3k6fRAGc45M4PKP2+7kVD8JxyotVwGznLH0WQIm7PNYR99wGGN9FrZuKVWVT17TkphSzGnOJgn ErkeXevOFFlAze3IFnXtWmVsIgvuyRp8legrNUNChroDdlshSrbE6l0ZuSbYHjA5IhQ3PO2ZbqB 3psH4RBsb3gU+8G+Bqzo2mZGK02HFd3RM6bmTP471NSo/Vv6qH251a6EIvnRpJPYKeXEojuziH6 ork+Odt/jIC/5KFXpzQ== X-Authority-Analysis: v=2.4 cv=OMcXGyaB c=1 sm=1 tr=0 ts=69d81bcf cx=c_pps a=EVbN6Ke/fEF3bsl7X48z0g==:117 a=xqWC_Br6kY4A:10 a=8nJEP1OIZ-IA:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=F7xsp-YMIWaRqylmYmQA:9 a=3ZKOabzyN94A:10 a=wPNLvfGTeEIA:10 a=a_PwQJl-kcHnX1M80qC6:22 X-Proofpoint-GUID: Y9c9hjHUAoliZhjywkcp32oqouT6tEYE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-09_04,2026-04-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 clxscore=1015 impostorscore=0 spamscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 malwarescore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604090199 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Apr 09, 2026 at 11:36:21PM +0300, Ville Syrj=E4l=E4 wrote: > On Thu, Apr 09, 2026 at 07:08:16PM +0200, Kory Maincent wrote: > > DisplayPort link training negotiates the physical-layer parameters need= ed > > for a reliable connection: lane count, link rate, voltage swing, > > pre-emphasis, and optionally Display Stream Compression (DSC). Currentl= y, > > each driver exposes this state in its own way, often through > > driver-specific debugfs entries, with no standard interface for userspa= ce > > diagnostic and monitoring tools. > >=20 > > This series introduces a generic, DRM-managed framework for exposing DP > > link training state as standard connector properties, modeled after the > > existing HDMI helper drmm_connector_hdmi_init(). > >=20 > > The new drmm_connector_dp_init() helper initializes a DP connector and > > registers the following connector properties to expose the negotiated l= ink > > state to userspace: > >=20 > > - num_lanes: negotiated lane count (1, 2 or 4) > > - link_rate: negotiated link rate > > - dsc_en: whether Display Stream Compression is active > > - voltage_swingN: per-lane voltage swing level (lanes 0-3) > > - pre_emphasisN: per-lane pre-emphasis level (lanes 0-3) >=20 > I don't see why any real userspace would be interested in those (apart > from maybe DSC). If this is just for diagnostics and whatnot then I > think sysfs/debugfs could be a better fit. I'd agree here. Please consider implementing it as a debugfs interface, possibly reusing the Intel's format. --=20 With best wishes Dmitry