[PATCH v2 1/3] drm/todo: Create a TODO item for additional HDMI work

[Maxime Ripard]

We recently added some infrastructure to deal with HDMI but we're still
lacking a couple of things. Add a TODO entry with the remaining items.

Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
Signed-off-by: Maxime Ripard <mripard at kernel.org>

---

Changes from v1:
  - Add sound and HDCP
---
 Documentation/gpu/todo.rst | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 2ea6ffc9b22b..3104ffbd6295 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -633,10 +633,46 @@ long as that supports DMA. Otherwise importing can still needlessly fail.
 
 Contact: Thomas Zimmermann <tzimmermann at suse.de>, Daniel Vetter
 
 Level: Advanced
 
+Improve HDMI Infrastructure
+---------------------------
+
+We have a bunch of helpers to handle HDMI and reduce the boilerplate in
+drivers. Support so far includes HDMI 1.4 support, but we need to extend
+it with:
+
+  - CEC handling support. CEC requires a bit of integration into every
+    HDMI driver to set the device physical address according to the EDID
+    in `.get_modes`, and to clear/reset it in the hotplug detection
+    path. We should create the ``drm_atomic_helper_connector_hdmi_get_modes()``
+    and ``drm_atomic_helper_connector_hdmi_handle_hotplug()`` helpers to handle
+    this properly, and convert drivers to use them.
+
+  - In order to support HDMI 2.0 properly, the scrambler parameters need
+    to be moved into the state. This includes figuring out in
+    drm_atomic_helper_connector_hdmi_check() if the scrambler and TMDS ratio
+    need to be changed, and make the
+    ``drm_atomic_helper_connector_hdmi_handle_hotplug()`` helper reset the
+    scrambler status when the device is plugged and unplugged.
+
+  - We need to support YUV420 too.
+
+  - Make the audio support somewhat generic too. The lowest hanging fruits
+    would be to provide helpers for `get_eld`, to handle hotplug and compute
+    ACR, N, and CTS parameters.
+
+  - Handling HDCP in a generic manner would be a good idea too.
+    See `[PATCH v10 00/10] drm/hdcp: Pull HDCP auth/exchange/check into helpers <https://lore.kernel.org/dri-devel/20230419154321.1993419-1-markyacoub@google.com/>`_
+
+The `vc4` driver is a good example for all this.
+
+Contact: Maxime Ripard <mripard at kernel.org>
+
+Level: Intermediate
+
 
 Better Testing
 ==============
 
 Add unit tests using the Kernel Unit Testing (KUnit) framework
-- 
2.45.2