kernel/linux.git/drivers/gpu/drm/display, branch v6.1.186

drm/dp: Read the PCON max FRL bandwidth only for HDMI DFPs

2026-08-19T15:16:21+00:00

commit e40e20ac089e32f1d910636155dc82e61e61dcf3 upstream. The PCON max FRL bandwidth field lives in byte 2 of the DFP Detailed Capability Info (DPCD 0x82 for the first DFP). The DP standard defines the meaning of descriptor bytes 1-3 strictly per DFP type, and for a DisplayPort type DFP all of them are reserved, with "read all 0s" semantics (DP v2.0, section 2.12.3, Table 2-183). The FRL bandwidth field is an HDMI DFP extension added by the VESA DP-to-HDMI PCON specification. drm_dp_get_pcon_max_frl_bw() however parses the byte without checking the DFP type, the branch presence or DETAILED_CAP_INFO_AVAILABLE. Without the latter the port descriptors are one byte wide and port_cap[2] is not even the right register. All neighbouring helpers parsing the same descriptor are scoped by the DFP type already, see for instance drm_dp_downstream_max_bpc() reading the same byte and returning 0 for a DP type DFP. amdgpu's DC parses the field only for HDMI(/DP++) detailed types as well. This is not theoretical. A Synaptics VMM7100 based USB-C to HDMI adapter with a macOS targeted firmware advertises a DisplayPort type DFP with the type byte replicated across the whole descriptor (08 08 08 08). i915 decodes that as "PCON limited to 18 Gbps FRL" and prunes every mode above ~750 MHz dotclock, including all the 4k@100/120 modes the sink EDID offers, while macOS drives 4k@120 through the same adapter just fine via DP DSC (and amdgpu's type-scoped parser would ignore the bogus field as well). Only parse the field for an HDMI DFP behind a DPCD 1.1+ branch device that reports detailed cap info, matching the type-scoped field layout of the spec and the rest of the helpers. Fixes: ce32a6239de6 ("drm/dp_helper: Add Helpers for FRL Link Training support for DP-HDMI2.1 PCON") Cc: Ankit Nautiyal Cc: Uma Shankar (v2) Cc: Jani Nikula Cc: Maarten Lankhorst Cc: dri-devel@lists.freedesktop.org Cc: # v5.12+ Signed-off-by: Alexander Kaplan Reviewed-by: Ankit Nautiyal Signed-off-by: Ankit Nautiyal Link: https://patch.msgid.link/20260610193825.2933-1-alexander.kaplan@sms-medipool.de Signed-off-by: Greg Kroah-Hartman

drm/dp/mst: fix OOB reads on 2-byte fields in sideband reply parsers

2026-08-19T15:16:02+00:00

commit 6b89ba3dba2f583626fb693e47e951ffb8bf591f upstream. Three sideband reply parsers read 16-bit fields as: val = (raw->msg[idx] << 8) | (raw->msg[idx+1]); and check bounds only after the fact. When idx == raw->curlen, raw->msg[idx+1] reads one byte past the received message data into the following struct fields (curchunk_len, curchunk_idx, curlen). Affected functions: - drm_dp_sideband_parse_enum_path_resources_ack() full_payload_bw_number and avail_payload_bw_number fields - drm_dp_sideband_parse_allocate_payload_ack() allocated_pbn field - drm_dp_sideband_parse_query_payload_ack() allocated_pbn field Fix by using a single combined check (idx + 2 > curlen) before each 2-byte read. Since the check is strictly tighter than idx > curlen, no separate step is needed. Fixes: ad7f8a1f9ced ("drm/helper: add Displayport multi-stream helper (v0.6)") Cc: # v3.17+ Signed-off-by: Ashutosh Desai Reviewed-by: Lyude Paul [added fixes tag] Signed-off-by: Lyude Paul Link: https://patch.msgid.link/20260510203128.2884846-1-ashutoshdesai993@gmail.com Signed-off-by: Greg Kroah-Hartman

drm/dp/mst: fix buffer overflows in sideband chunk accumulation

2026-08-19T15:16:02+00:00

commit 55bd5e685bda455b9b50c835f8c8442d52a344a3 upstream. drm_dp_sideband_append_payload() has three related bugs when processing device-provided sideband reply data: 1. Zero-length curchunk_len underflow: msg_len is a 6-bit field taken directly from the DP sideband header. If a device sends msg_len=0, curchunk_len is set to zero. The condition (curchunk_idx >= curchunk_len) is immediately true, and curchunk_len-1 wraps to 255 (u8 underflow). drm_dp_msg_data_crc4() reads 255 bytes from chunk[48], then memcpy() writes 255 bytes into msg[], both far out of bounds. 2. chunk[48] overflow: curchunk_len can reach 63 (6-bit field). chunk[] is only 48 bytes. Multi-iteration payload assembly appends 16-byte blocks until curchunk_idx reaches curchunk_len, writing up to 15 bytes past the end of chunk[] into msg[]. 3. msg[256] overflow: each chunk contributes (curchunk_len-1) bytes to msg[]. No check ensures curlen + (curchunk_len-1) stays within msg[256], so the memcpy can spill into adjacent struct fields. All three are reachable from any DP MST device that can forge sideband reply messages on a physical connection. Fixes: ad7f8a1f9ced ("drm/helper: add Displayport multi-stream helper (v0.6)") Cc: # v3.17+ Signed-off-by: Ashutosh Desai Reviewed-by: Lyude Paul Signed-off-by: Lyude Paul Link: https://patch.msgid.link/20260410041901.2438960-1-ashutoshdesai993@gmail.com Signed-off-by: Greg Kroah-Hartman

drm/dp/mst: fix OOB reads in remote DPCD/I2C sideband reply parsers

2026-08-19T15:16:02+00:00

commit 1a8f537f5a1eeac941f262fe73078d6b08ba83c0 upstream. drm_dp_sideband_parse_remote_dpcd_read() reads num_bytes from the raw message and then unconditionally does: memcpy(bytes, &raw->msg[idx], num_bytes); without checking that idx + num_bytes <= raw->curlen. raw->msg[] is 256 bytes; if a malicious or misbehaving MST hub sets num_bytes larger than the remaining payload, the memcpy reads past the received data into whatever follows in raw->msg[]. drm_dp_sideband_parse_remote_i2c_read_ack() has the same flaw (noted with a /* TODO check */ comment since the code was introduced). Fix both functions by using a single combined check (idx + num_bytes > curlen) before each memcpy. Since num_bytes is u8, it is always >= 0, so this strictly subsumes the simpler idx > curlen form and no separate step is needed. Fixes: ad7f8a1f9ced ("drm/helper: add Displayport multi-stream helper (v0.6)") Cc: # v3.17+ Signed-off-by: Ashutosh Desai Reviewed-by: Lyude Paul [added missing fixes tag] Signed-off-by: Lyude Paul Link: https://patch.msgid.link/20260510201733.2882224-1-ashutoshdesai993@gmail.com Signed-off-by: Greg Kroah-Hartman

drm/display/dp_mst: Add protection against 0 vcpi

2026-03-04T12:20:18+00:00

[ Upstream commit 342ccffd9f77fc29fe1c05fd145e4d842bd2feaa ] When releasing a timeslot there is a slight chance we may end up with the wrong payload mask due to overflow if the delayed_destroy_work ends up coming into play after a DP 2.1 monitor gets disconnected which causes vcpi to become 0 then we try to make the payload = ~BIT(vcpi - 1) which is a negative shift. VCPI id should never really be 0 hence skip changing the payload mask if VCPI is 0. Otherwise it leads to <7> [515.287237] xe 0000:03:00.0: [drm:drm_dp_mst_get_port_malloc [drm_display_helper]] port ffff888126ce9000 (3) <4> [515.287267] -----------[ cut here ]----------- <3> [515.287268] UBSAN: shift-out-of-bounds in ../drivers/gpu/drm/display/drm_dp_mst_topology.c:4575:36 <3> [515.287271] shift exponent -1 is negative <4> [515.287275] CPU: 7 UID: 0 PID: 3108 Comm: kworker/u64:33 Tainted: G S U 6.17.0-rc6-lgci-xe-xe-3795-3e79699fa1b216e92+ #1 PREEMPT(voluntary) <4> [515.287279] Tainted: [S]=CPU_OUT_OF_SPEC, [U]=USER <4> [515.287279] Hardware name: ASUS System Product Name/PRIME Z790-P WIFI, BIOS 1645 03/15/2024 <4> [515.287281] Workqueue: drm_dp_mst_wq drm_dp_delayed_destroy_work [drm_display_helper] <4> [515.287303] Call Trace: <4> [515.287304] <4> [515.287306] dump_stack_lvl+0xc1/0xf0 <4> [515.287313] dump_stack+0x10/0x20 <4> [515.287316] __ubsan_handle_shift_out_of_bounds+0x133/0x2e0 <4> [515.287324] ? drm_atomic_get_private_obj_state+0x186/0x1d0 <4> [515.287333] drm_dp_atomic_release_time_slots.cold+0x17/0x3d [drm_display_helper] <4> [515.287355] mst_connector_atomic_check+0x159/0x180 [xe] <4> [515.287546] drm_atomic_helper_check_modeset+0x4d9/0xfa0 <4> [515.287550] ? __ww_mutex_lock.constprop.0+0x6f/0x1a60 <4> [515.287562] intel_atomic_check+0x119/0x2b80 [xe] <4> [515.287740] ? find_held_lock+0x31/0x90 <4> [515.287747] ? lock_release+0xce/0x2a0 <4> [515.287754] drm_atomic_check_only+0x6a2/0xb40 <4> [515.287758] ? drm_atomic_add_affected_connectors+0x12b/0x140 <4> [515.287765] drm_atomic_commit+0x6e/0xf0 <4> [515.287766] ? _pfx__drm_printfn_info+0x10/0x10 <4> [515.287774] drm_client_modeset_commit_atomic+0x25c/0x2b0 <4> [515.287794] drm_client_modeset_commit_locked+0x60/0x1b0 <4> [515.287795] ? mutex_lock_nested+0x1b/0x30 <4> [515.287801] drm_client_modeset_commit+0x26/0x50 <4> [515.287804] __drm_fb_helper_restore_fbdev_mode_unlocked+0xdc/0x110 <4> [515.287810] drm_fb_helper_hotplug_event+0x120/0x140 <4> [515.287814] drm_fbdev_client_hotplug+0x28/0xd0 <4> [515.287819] drm_client_hotplug+0x6c/0xf0 <4> [515.287824] drm_client_dev_hotplug+0x9e/0xd0 <4> [515.287829] drm_kms_helper_hotplug_event+0x1a/0x30 <4> [515.287834] drm_dp_delayed_destroy_work+0x3df/0x410 [drm_display_helper] <4> [515.287861] process_one_work+0x22b/0x6f0 <4> [515.287874] worker_thread+0x1e8/0x3d0 <4> [515.287879] ? __pfx_worker_thread+0x10/0x10 <4> [515.287882] kthread+0x11c/0x250 <4> [515.287886] ? __pfx_kthread+0x10/0x10 <4> [515.287890] ret_from_fork+0x2d7/0x310 <4> [515.287894] ? __pfx_kthread+0x10/0x10 <4> [515.287897] ret_from_fork_asm+0x1a/0x30 Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6303 Signed-off-by: Suraj Kandpal Reviewed-by: Imre Deak Reviewed-by: Lyude Paul Link: https://patch.msgid.link/20251119094650.799135-1-suraj.kandpal@intel.com Signed-off-by: Sasha Levin

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

2025-09-04T13:26:31+00:00

This reverts commit 4f546a77671076a0a49c08b4c6a7d0888d72f7d2 which is commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f upstream. The upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ("drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS") the reverted commit backported causes a regression, on one eDP panel at least resulting in display flickering, described in detail at the Link: below. The issue fixed by the upstream commit will need a different solution, revert the backport for now. Cc: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Cc: Sasha Levin Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14558 Signed-off-by: Imre Deak Signed-off-by: Greg Kroah-Hartman

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

2025-08-28T14:26:16+00:00

[ Upstream commit a40c5d727b8111b5db424a1e43e14a1dcce1e77f ] 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 Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

drm/dp_mst: Fix drm RAD print

2025-04-10T12:33:32+00:00

[ Upstream commit 6bbce873a9c97cb12f5455c497be279ac58e707f ] [Why] The RAD of sideband message printed today is incorrect. For RAD stored within MST branch - If MST branch LCT is 1, it's RAD array is untouched and remained as 0. - If MST branch LCT is larger than 1, use nibble to store the up facing port number in cascaded sequence as illustrated below: u8 RAD[0] = (LCT_2_UFP << 4) | LCT_3_UFP RAD[1] = (LCT_4_UFP << 4) | LCT_5_UFP ... In drm_dp_mst_rad_to_str(), it wrongly to use BIT_MASK(4) to fetch the port number of one nibble. [How] Adjust the code by: - RAD array items are valuable only for LCT >= 1. - Use 0xF as the mask to replace BIT_MASK(4) V2: - Document how RAD is constructed (Imre) V3: - Adjust the comment for rad[] so kdoc formats it properly (Lyude) Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing + selftests") Cc: Imre Deak Cc: Ville Syrjälä Cc: Harry Wentland Cc: Lyude Paul Reviewed-by: Lyude Paul Signed-off-by: Wayne Lin Signed-off-by: Lyude Paul Link: https://patchwork.freedesktop.org/patch/msgid/20250113091100.3314533-2-Wayne.Lin@amd.com Signed-off-by: Sasha Levin

drm/dp_mst: Fix locking when skipping CSN before topology probing

2025-03-28T20:58:56+00:00

commit 12d8f318347b1d4feac48e8ac351d3786af39599 upstream. The handling of the MST Connection Status Notify message is skipped if the probing of the topology is still pending. Acquiring the drm_dp_mst_topology_mgr::probe_lock for this in drm_dp_mst_handle_up_req() is problematic: the task/work this function is called from is also responsible for handling MST down-request replies (in drm_dp_mst_handle_down_rep()). Thus drm_dp_mst_link_probe_work() - holding already probe_lock - could be blocked waiting for an MST down-request reply while drm_dp_mst_handle_up_req() is waiting for probe_lock while processing a CSN message. This leads to the probe work's down-request message timing out. A scenario similar to the above leading to a down-request timeout is handling a CSN message in drm_dp_mst_handle_conn_stat(), holding the probe_lock and sending down-request messages while a second CSN message sent by the sink subsequently is handled by drm_dp_mst_handle_up_req(). Fix the above by moving the logic to skip the CSN handling to drm_dp_mst_process_up_req(). This function is called from a work (separate from the task/work handling new up/down messages), already holding probe_lock. This solves the above timeout issue, since handling of down-request replies won't be blocked by probe_lock. Fixes: ddf983488c3e ("drm/dp_mst: Skip CSN if topology probing is not done yet") Cc: Wayne Lin Cc: Lyude Paul Cc: stable@vger.kernel.org # v6.6+ Reviewed-by: Wayne Lin Reviewed-by: Lyude Paul Signed-off-by: Imre Deak Link: https://patchwork.freedesktop.org/patch/msgid/20250307183152.3822170-1-imre.deak@intel.com Signed-off-by: Greg Kroah-Hartman

gpu: drm_dp_cec: fix broken CEC adapter properties check

2025-02-21T12:49:36+00:00

[ Upstream commit 6daaae5ff7f3b23a2dacc9c387ff3d4f95b67cad ] If the hotplug detect of a display is low for longer than one second (configurable through drm_dp_cec_unregister_delay), then the CEC adapter is unregistered since we assume the display was disconnected. If the HPD went low for less than one second, then we check if the properties of the CEC adapter have changed, since that indicates that we actually switch to new hardware and we have to unregister the old CEC device and register a new one. Unfortunately, the test for changed properties was written poorly, and after a new CEC capability was added to the CEC core code the test always returned true (i.e. the properties had changed). As a result the CEC device was unregistered and re-registered for every HPD toggle. If the CEC remote controller integration was also enabled (CONFIG_MEDIA_CEC_RC was set), then the corresponding input device was also unregistered and re-registered. As a result the input device in /sys would keep incrementing its number, e.g.: /sys/devices/pci0000:00/0000:00:08.1/0000:e7:00.0/rc/rc0/input20 Since short HPD toggles are common, the number could over time get into the thousands. While not a serious issue (i.e. nothing crashes), it is not intended to work that way. This patch changes the test so that it only checks for the single CEC capability that can actually change, and it ignores any other capabilities, so this is now safe as well if new caps are added in the future. With the changed test the bit under #ifndef CONFIG_MEDIA_CEC_RC can be dropped as well, so that's a nice cleanup. Signed-off-by: Hans Verkuil Reported-by: Farblos Reviewed-by: Dmitry Baryshkov Fixes: 2c6d1fffa1d9 ("drm: add support for DisplayPort CEC-Tunneling-over-AUX") Tested-by: Farblos Link: https://patchwork.freedesktop.org/patch/msgid/361bb03d-1691-4e23-84da-0861ead5dbdc@xs4all.nl Signed-off-by: Dmitry Baryshkov Signed-off-by: Sasha Levin