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([171.61.166.126]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82339095c85sm5470337b3a.67.2026.01.26.12.49.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jan 2026 12:49:22 -0800 (PST) From: Atharva Tiwari To: jani.nikula@linux.intel.com Cc: airlied@gmail.com, atharvatiwarilinuxdev@gmail.com, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, joonas.lahtinen@linux.intel.com, linux-kernel@vger.kernel.org, rodrigo.vivi@intel.com, simona@ffwll.ch, tursulin@ursulin.net, ville.syrjala@linux.intel.com Subject: Re: [PATCH 2/2] drm/i915/display: Disable display for iMac's Date: Mon, 26 Jan 2026 20:49:15 +0000 Message-ID: <20260126204915.1324-1-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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" > Rendering and display are quite separate in the hardware and in the > driver. Perhaps you do not mean "rendering" here? Perhaps it can be used > for rendering but not display? Yeah, it can be used for rendering but not display, sorry for the wording. > Okay, so perhaps there's no eDP connected. But what about the other > connectors on the iGPU? What about everything else in the display > hardware? You cant use the iGPU to drive the display on any hardware (including external displays). > If you can figure out that it's specifically link training that fails (a > dmesg would be useful to show this) there clearly is display hardware, > right? As said the iGPU cant drive the display on all monitors (even on macOS), but still heres the dmesg before this patch: [ 5.095489] i915 0000:00:02.0: [drm] Found cometlake (device ID 9bc8) integrated display version 9.00 stepping N/A [ 5.096061] i915 0000:00:02.0: [drm] VT-d active for gfx access [ 5.096102] i915 0000:00:02.0: [drm] Using Transparent Hugepages [ 5.099214] i915 0000:00:02.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xffff [ 5.099217] i915 0000:00:02.0: [drm] Failed to find VBIOS tables (VBT) [ 5.099324] i915 0000:00:02.0: vgaarb: VGA decodes changed: olddecodes=io+mem,decodes=none:owns=io+mem [ 5.100960] i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4) [ 5.832214] i915 0000:00:02.0: [drm] [ENCODER:105:DDI A/PHY A] failed to retrieve link info, disabling eDP [ 5.835756] i915 0000:00:02.0: [drm] Registered 3 planes with drm panic [ 6.428455] i915 0000:00:02.0: [drm] Cannot find any crtc or sizes [ 6.722404] i915 0000:00:02.0: [drm] Cannot find any crtc or sizes > There's at least three levels where this could be handled, depending on > details: > > - Display probe (the patch at hand). Assumes there's no display > hardware, at all. The driver doesn't touch the hardware, which > continues to consume power, it's not put in low power states. Not > optimal if there actually is display hardware. > > - Display disable. See intel_display_device_enabled(). The driver takes > over the hardware, puts it to sleep, but prevents all connectors from > being connected. > > - eDP disable. Add a quirk somewhere to enforce eDP is disconnected, but > other connectors can be used. The main reason I sent this patch is that after i915 trys to probe the display, the dGPU (amdgpu) is no longer able to detect the internal display, resulting in a black screen. > It would be quite useful to indicate the PCI ID of the device in > question. 00:02.0 VGA compatible controller [0300]: Intel Corporation CometLake-S GT2 [UHD Graphics 630] [8086:9bc8] (rev 03) (prog-if 00 [VGA controller]) Subsystem: Apple Inc. CometLake-S GT2 [UHD Graphics 630] [106b:ffff]