linux/drivers/gpu/drm/display, branch v6.16

drm/dp: Change AUX DPCD probe address from LANE0_1_STATUS to TRAINING_PATTERN_SET

2025-07-15T13:37:57Z

Commit a3ef3c2da675 ("drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") stopped using the DPCD_REV register for DPCD probing, since this results in link training failures at least when using an Intel Barlow Ridge TBT hub at UHBR link rates (the DP_INTRA_HOP_AUX_REPLY_INDICATION never getting cleared after the failed link training). Since accessing DPCD_REV during link training is prohibited by the DP Standard, LANE0_1_STATUS (0x202) was used instead, as it falls within the Standard's valid register address range (0x102-0x106, 0x202-0x207, 0x200c-0x200f, 0x2216) and it fixed the link training on the above TBT hub. However, reading the LANE0_1_STATUS register also has a side-effect at least on a Novatek eDP panel, as reported on the Closes: link below, resulting in screen flickering on that panel. One clear side-effect when doing the 1-byte probe reads from LANE0_1_STATUS during link training before reading out the full 6 byte link status starting at the same address is that the panel will report the link training as completed with voltage swing 0. This is different from the normal, flicker-free scenario when no DPCD probing is done, the panel reporting the link training complete with voltage swing 2. Using the TRAINING_PATTERN_SET register for DPCD probing doesn't have the above side-effect, the panel will link train with voltage swing 2 as expected and it will stay flicker-free. This register is also in the above valid register range and is unlikely to have a side-effect as that of LANE0_1_STATUS: Reading LANE0_1_STATUS is part of the link training CR/EQ sequences and so it may cause a state change in the sink - even if inadvertently as I suspect in the case of the above Novatek panel. As opposed to this, reading TRAINING_PATTERN_SET is not part of the link training sequence (it must be only written once at the beginning of the CR/EQ sequences), so it's unlikely to cause any state change in the sink. As a side-note, this Novatek panel also lacks support for TPS3, while claiming support for HBR2, which violates the DP Standard (the Standard mandating TPS3 for HBR2). Besides the Novatek panel (PSR 1), which this change fixes, I also verified the change on a Samsung (PSR 1) and an Analogix (PSR 2) eDP panel as well as on the Intel Barlow Ridge TBT hub. Note that in the drm-tip tree (targeting the v6.17 kernel version) the i915 and xe drivers keep DPCD probing enabled only for the panel known to require this (HP ZR24w), hence those drivers in drm-tip are not affected by the above problem. Cc: Ville Syrjälä Cc: Jani Nikula Fixes: a3ef3c2da675 ("drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") Reported-and-tested-by: Paul Menzel Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558 Reviewed-by: Jonathan Cavitt Acked-by: Thomas Zimmermann Link: https://lore.kernel.org/r/20250708212331.112898-1-imre.deak@intel.com (cherry picked from commit bba9aa41654036534d86b198f5647a9ce15ebd7f) [Imre: Rebased on drm-intel-fixes] Signed-off-by: Imre Deak Signed-off-by: Rodrigo Vivi [Rodrigo: Changed original commit hash to match with the one propagated in fixes]

Merge tag 'drm-misc-fixes-2025-06-26' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-fixes

2025-06-27T20:53:00Z

drm-misc-fixes for v6.16-rc4: - Fix function signature of drm_writeback_connector_cleanup. - Use correct HDMI audio bridge in drm_connector_hdmi_audio_init. - Make HPD work on SN65DSI86. Signed-off-by: Dave Airlie From: Maarten Lankhorst Link: https://lore.kernel.org/r/3dd1d5e1-73b6-4b0c-a208-f7d6235cf530@linux.intel.com

drm/bridge-connector: Fix bridge in drm_connector_hdmi_audio_init()

2025-06-23T22:17:21Z

The bridge used in drm_connector_hdmi_audio_init() does not correctly point to the required audio bridge, which lead to incorrect audio configuration input. Fixes: 231adeda9f67 ("drm/bridge-connector: hook DisplayPort audio support") Signed-off-by: Chaoyi Chen Reviewed-by: Dmitry Baryshkov Tested-by: Stephan Gerhold Link: https://lore.kernel.org/r/20250620011616.118-1-kernel@airkyi.com Signed-off-by: Dmitry Baryshkov

drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS

2025-06-23T12:53:42Z

Reading DPCD registers has side-effects in general. In particular accessing registers outside of the link training register range (0x102-0x106, 0x202-0x207, 0x200c-0x200f, 0x2216) is explicitly forbidden by the DP v2.1 Standard, see 3.6.5.1 DPTX AUX Transaction Handling Mandates 3.6.7.4 128b/132b DP Link Layer LTTPR Link Training Mandates Based on my tests, accessing the DPCD_REV register during the link training of an UHBR TBT DP tunnel sink leads to link training failures. Solve the above by using the DP_LANE0_1_STATUS (0x202) register for the DPCD register access quirk. Cc: Cc: Ville Syrjälä Cc: Jani Nikula Acked-by: Jani Nikula Signed-off-by: Imre Deak Link: https://lore.kernel.org/r/20250605082850.65136-2-imre.deak@intel.com (cherry picked from commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f) Signed-off-by: Joonas Lahtinen

drm/connector: only call HDMI audio helper plugged cb if non-null

2025-05-27T20:08:21Z

On driver remove, sound/soc/codecs/hdmi-codec.c calls the plugged_cb with NULL as the callback function and codec_dev, as seen in its hdmi_remove function. The HDMI audio helper then happily tries calling said null function pointer, and produces an Oops as a result. Fix this by only executing the callback if fn is non-null. This means the .plugged_cb and .plugged_cb_dev members still get appropriately cleared. Fixes: baf616647fe6 ("drm/connector: implement generic HDMI audio helpers") Signed-off-by: Nicolas Frattaroli Reviewed-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20250527-hdmi-audio-helper-remove-fix-v1-1-6cf77de364d8@collabora.com Signed-off-by: Dmitry Baryshkov

drm/dp: add option to disable zero sized address only transactions.

2025-05-18T21:14:45Z

Some older NVIDIA and some newer NVIDIA hardware/firmware seems to have issues with address only transactions (firmware rejects them). Add an option to the core drm dp to avoid address only transactions, This just puts the MOT flag removal on the last message of the transfer and avoids the start of transfer transaction. This with the flag set in nouveau, allows eDP probing on GB203 device. Signed-off-by: Dave Airlie Reviewed-by: Ben Skeggs Reviewed-by: Timur Tabi Tested-by: Timur Tabi Signed-off-by: Dave Airlie

Merge tag 'drm-intel-next-2025-05-08' of https://gitlab.freedesktop.org/drm/i915/kernel into drm-next

2025-05-09T20:12:18Z

Non-display related: - Fix undefined reference to `intel_pxp_gsccs_is_ready_for_sessions' Display related: - More work towards display separation (Jani) - Stop writing VRR_CTL_IGN_MAX_SHIFT for MTL onwards (Jouni) - DSC checks for 3 engines (Ankit) - Add link rate and lane count to i915_display_info (Khaled) - PSR fixes and workaround for underrun on idle (Jouni) - LOBF enablement and ALMP fixes (Animesh) - Clean up VGA plane handling (Ville) - Use an intel_connector pointer everywhere (Imre) - Fix warning for coffeelake on SunrisePoint PCH (Jiajia) - Rework/Correction on minimum hblank calculation (Arun) - Dmesg clean up (Jani) - Add a couple of simple display workarounds (Ankit, Vinod) - Refactor HDCP GSC (Jani) Signed-off-by: Dave Airlie From: Rodrigo Vivi Link: https://lore.kernel.org/r/aByyL3bEufPu79OM@intel.com

drm/display/dp: Export fn to calculate link symbol cycles

2025-04-30T19:07:38Z

Unify the function to calculate the link symbol cycles for both dsc and non-dsc case and export the function so that it can be used in the respective platform display drivers for other calculations. v2: unify the fn for both dsc and non-dsc case (Imre) v3: rename drm_dp_link_symbol_cycles to drm_dp_link_data_symbol_cycles retain slice_eoc_cycles as is (Imre) v4: Expose only drm_dp_link_symbol_cycles() (Imre) v6: Add slice pixels which was removed unknowingly (Vinod) Signed-off-by: Arun R Murthy Reviewed-by: Imre Deak Reviewed-by: Vinod Govindapillai Acked-by: Maarten Lankhorst Signed-off-by: Imre Deak Link: https://lore.kernel.org/r/20250424-hblank-v7-1-8b002f1506cc@intel.com

drm/display: hdmi: provide central data authority for ACR params

2025-04-15T11:05:14Z

HDMI standard defines recommended N and CTS values for Audio Clock Regeneration. Currently each driver implements those, frequently in somewhat unique way. Provide a generic helper for getting those values to be used by the HDMI drivers. The helper is added to drm_hdmi_helper.c rather than drm_hdmi_audio.c since HDMI drivers can be using this helper function even without switching to DRM HDMI Audio helpers. Note: currently this only handles the values per HDMI 1.4b Section 7.2 and HDMI 2.0 Section 9.2.1. Later the table can be expanded to accommodate for Deep Color TMDS char rates per HDMI 1.4 Appendix D and/or HDMI 2.0 / 2.1 Appendix C). Reviewed-by: Maxime Ripard Link: https://lore.kernel.org/r/20250408-drm-hdmi-acr-v2-1-dee7298ab1af@oss.qualcomm.com Signed-off-by: Dmitry Baryshkov

drm/bridge-connector: hook DisplayPort audio support

2025-04-07T12:49:19Z

Reuse existing code plumbing HDMI audio support and the existing HDMI audio helpers that register HDMI codec device and plumb in the DisplayPort audio interfaces to be handled by the drm_bridge_connector. Reviewed-by: Maxime Ripard Link: https://lore.kernel.org/r/20250314-dp-hdmi-audio-v6-3-dbd228fa73d7@oss.qualcomm.com Signed-off-by: Dmitry Baryshkov