[PATCH] drm/todo: Update panic handling todo

[Daniel Vetter]

Some things changed, and add two useful links.

v2: Also include a link to the QR encoding work. Plus review from
Javier.

Reviewed-by: Javier Martinez Canillas <javierm at redhat.com>
Cc: Javier Martinez Canillas <javierm at redhat.com>
Cc: Pekka Paalanen <ppaalanen at gmail.com>
Cc: gpiccoli at igalia.com
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 Documentation/gpu/todo.rst | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 7bf7f2111696..2b1e7fa45603 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -475,8 +475,12 @@ This is a really varied tasks with lots of little bits and pieces:
   achieved by using an IPI to the local processor.
 
 * There's a massive confusion of different panic handlers. DRM fbdev emulation
-  helpers have one, but on top of that the fbcon code itself also has one. We
-  need to make sure that they stop fighting over each another.
+  helpers had their own (long removed), but on top of that the fbcon code itself
+  also has one. We need to make sure that they stop fighting over each other.
+  This is worked around by checking ``oops_in_progress`` at various entry points
+  into the DRM fbdev emulation helpers. A much cleaner approach here would be to
+  switch fbcon to the `threaded printk support
+  <https://lwn.net/Articles/800946/>`_.
 
 * ``drm_can_sleep()`` is a mess. It hides real bugs in normal operations and
   isn't a full solution for panic paths. We need to make sure that it only
@@ -488,16 +492,15 @@ This is a really varied tasks with lots of little bits and pieces:
   even spinlocks (because NMI and hardirq can panic too). We need to either
   make sure to not call such paths, or trylock everything. Really tricky.
 
-* For the above locking troubles reasons it's pretty much impossible to
-  attempt a synchronous modeset from panic handlers. The only thing we could
-  try to achive is an atomic ``set_base`` of the primary plane, and hope that
-  it shows up. Everything else probably needs to be delayed to some worker or
-  something else which happens later on. Otherwise it just kills the box
-  harder, prevent the panic from going out on e.g. netconsole.
+* A clean solution would be an entirely separate panic output support in KMS,
+  bypassing the current fbcon support. See `[PATCH v2 0/3] drm: Add panic handling
+  <https://lore.kernel.org/dri-devel/20190311174218.51899-1-noralf@tronnes.org/>`_.
 
-* There's also proposal for a simplied DRM console instead of the full-blown
-  fbcon and DRM fbdev emulation. Any kind of panic handling tricks should
-  obviously work for both console, in case we ever get kmslog merged.
+* Encoding the actual oops and preceeding dmesg in a QR might help with the
+  dread "important stuff scrolled away" problem. See `[RFC][PATCH] Oops messages
+  transfer using QR codes
+  <https://lore.kernel.org/lkml/1446217392-11981-1-git-send-email-alexandru.murtaza@intel.com/>`_
+  for some example code that could be reused.
 
 Contact: Daniel Vetter
 
-- 
2.34.1