commit 3f17bc0953a6efae769c26ba116a7e936303315c
author Paul Howgego <paul.howgego@arm.com> Tue Jun 09 18:21:45 2020 +0100
committer John Stultz <john.stultz@linaro.org> Fri Jun 26 22:57:10 2020 +0000
tree 2daa323bafa9290dd55f0bb4307b4e07fc244bc3
parent a63d66c7bbb2b990e86040eb646540924bd20a23

drm_hwcomposer: Fix invalid buffer_handle_t pointer

In Android 11, at boot time, I see the following sequence of
calls from SurfaceFlinger that trigger this:

  // Composition type for layer is saved in DRM HWC Layer validated_type_
  validateDisplay()

  // Layer composition type saved in DRM HWC Layer sf_type_
  acceptDisplayChanges()

  // Composition type in Layer sf_type_ is now "client" so DRM HWC doesn't
  // update the Layer buffer pointer
  setLayerBuffer()

  // DRM HWC Layer sf_type_ is now changed back to "device"
  setLayerCompositionType()

  // DRM HWC iterates through the layers and finds that Layer composition
  // type in sf_type_ is "device"  so thinks it is fine to calls
  // importBuffer() but this Layer now has an invalid pointer as the
  // setLayerBuffer() was ignored.
  validateDisplay()

Thus this patch, changes the logic to always update the
buffer_handle_t pointer in setLayerBuffer regardless of
composition type rather than keeping the invalid buffer_handle_t
in the Layer obect. The composition type may be changed back to
device composition by setLayerCompositionType at which point the
Layer object needs to have saved the buffer_handle_t.

Not sure how we could reproduce the same sequence of calls on
another Android version.

Signed-off-by: Paul Howgego <paul.howgego@arm.com>
[jstultz: Reword and add context from merge request to the commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: I88a11ee2fee742d6154a482455a8532a95e681d3