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  1. 24 Apr, 2020 4 commits
  3. 23 Apr, 2020 1 commit
    • Lyude Paul's avatar
      Revert "drm/dp_mst: Remove single tx msg restriction." · 973a5909
      Lyude Paul authored 
      This reverts commit 6bb0942e.

Unfortunately it would appear that the rumors we've heard of sideband
message interleaving not being very well supported are true. On the
Lenovo ThinkPad Thunderbolt 3 dock that I have, interleaved messages
appear to just get dropped:

  [drm:drm_dp_mst_wait_tx_reply [drm_kms_helper]] timedout msg send
  00000000571ddfd0 2 1
  [dp_mst] txmsg cur_offset=2 cur_len=2 seqno=1 state=SENT path_msg=1 dst=00
  [dp_mst] 	type=ENUM_PATH_RESOURCES contents:
  [dp_mst] 		port=2

DP descriptor for this hub:
  OUI 90-cc-24 dev-ID SYNA3  HW-rev 1.0 SW-rev 3.12 quirks 0x0008

It would seem like as well that this is a somewhat well known issue in
the field. From section 5.4.2 of the DisplayPort 2.0 specification:

  There are MST Sink/Branch devices in the field that do not handle
  interleaved message transactions.

  To facilitate message transaction handling by downstream devices, an
  MST Source device shall generate message transactions in an atomic
  manner (i.e., the MST Source device shall not concurrently interleave
  multiple message transactions). Therefore, an MST Source device shall
  clear the Message_Sequence_No value in the Sideband_MSG_Header to 0.

  MST Source devices that support field policy updates by way of
  software should update the policy to forego the generation of
  interleaved message transactions.

This is a bit disappointing, as features like HDCP require that we send
a sideband request every ~2 seconds for each active stream. However,
there isn't really anything in the specification that allows us to
accurately probe for interleaved messages.

If it ends up being that we -really- need this in the future, we might
be able to whitelist hubs where interleaving is known to work-or maybe
try some sort of heuristics. But for now, let's just play it safe and
not use it.
Signed-off-by: default avatarLyude Paul <lyude@redhat.com>
Fixes: 6bb0942e ("drm/dp_mst: Remove single tx msg restriction.")
Cc: Wayne Lin <Wayne.Lin@amd.com>
Cc: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200423164225.680178-1-lyude@redhat.comReviewed-by: default avatarSean Paul <sean@poorly.run>
      973a5909
  5. 21 Apr, 2020 4 commits
  7. 20 Apr, 2020 1 commit
    • Thomas Zimmermann's avatar
      drm/ast: Allocate initial CRTC state of the correct size · f0adbc38
      Thomas Zimmermann authored 
      The ast driver inherits from DRM's CRTC state, but still uses the atomic
helper for struct drm_crtc_funcs.reset, drm_atomic_helper_crtc_reset().

The helper only allocates enough memory for the core CRTC state. That
results in an out-ouf-bounds access when duplicating the initial CRTC
state. Simplified backtrace shown below:

[   21.469321] ==================================================================
[   21.469434] BUG: KASAN: slab-out-of-bounds in ast_crtc_atomic_duplicate_state+0x84/0x100 [ast]
[   21.469445] Read of size 8 at addr ffff888036c1c5f8 by task systemd-udevd/382
[   21.469451]
[   21.469464] CPU: 2 PID: 382 Comm: systemd-udevd Tainted: G            E     5.5.0-rc6-1-default+ #214
[   21.469473] Hardware name: Sun Microsystems SUN FIRE X2270 M2/SUN FIRE X2270 M2, BIOS 2.05    07/01/2010
[   21.469480] Call Trace:
[   21.469501]  dump_stack+0xb8/0x110
[   21.469528]  print_address_description.constprop.0+0x1b/0x1e0
[   21.469557]  ? ast_crtc_atomic_duplicate_state+0x84/0x100 [ast]
[   21.469581]  ? ast_crtc_atomic_duplicate_state+0x84/0x100 [ast]
[   21.469597]  __kasan_report.cold+0x1a/0x35
[   21.469640]  ? ast_crtc_atomic_duplicate_state+0x84/0x100 [ast]
[   21.469665]  kasan_report+0xe/0x20
[   21.469693]  ast_crtc_atomic_duplicate_state+0x84/0x100 [ast]
[   21.469733]  drm_atomic_get_crtc_state+0xbf/0x1c0
[   21.469768]  __drm_atomic_helper_set_config+0x81/0x5a0
[   21.469803]  ? drm_atomic_plane_check+0x690/0x690
[   21.469843]  ? drm_client_rotation+0xae/0x240
[   21.469876]  drm_client_modeset_commit_atomic+0x230/0x390
[   21.469888]  ? __mutex_lock+0x8f0/0xbe0
[   21.469929]  ? drm_client_firmware_config.isra.0+0xa60/0xa60
[   21.469948]  ? drm_client_modeset_commit_force+0x28/0x230
[   21.470031]  ? memset+0x20/0x40
[   21.470078]  drm_client_modeset_commit_force+0x90/0x230
[   21.470110]  drm_fb_helper_restore_fbdev_mode_unlocked+0x5f/0xc0
[   21.470132]  drm_fb_helper_set_par+0x59/0x70
[   21.470155]  fbcon_init+0x61d/0xad0
[   21.470185]  ? drm_fb_helper_restore_fbdev_mode_unlocked+0xc0/0xc0
[   21.470232]  visual_init+0x187/0x240
[   21.470266]  do_bind_con_driver+0x2e3/0x460
[   21.470321]  do_take_over_console+0x20a/0x290
[   21.470371]  do_fbcon_takeover+0x85/0x100
[   21.470402]  register_framebuffer+0x2fd/0x490
[   21.470425]  ? kzalloc.constprop.0+0x10/0x10
[   21.470503]  __drm_fb_helper_initial_config_and_unlock+0xf2/0x140
[   21.470533]  drm_fbdev_client_hotplug+0x162/0x250
[   21.470563]  drm_fbdev_generic_setup+0xd2/0x155
[   21.470602]  ast_driver_load+0x688/0x850 [ast]
<...>
[   21.472625] ==================================================================

Allocating enough memory for struct ast_crtc_state in a custom ast CRTC
reset handler fixes the problem.

v2:
	* implement according to drm_atomic_helper_crtc_reset()
	* update state with __drm_atomic_helper_crtc_reset()
Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Fixes: 83be6a3c ("drm/ast: Introduce struct ast_crtc_state")
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200130094012.32140-1-tzimmermann@suse.de
      f0adbc38
  9. 19 Apr, 2020 1 commit
  11. 17 Apr, 2020 22 commits
  13. 16 Apr, 2020 1 commit
  15. 15 Apr, 2020 6 commits
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