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Documentation/gpu: Add asynchronous flip documentation for i915 

Add the details of the implementation of asynchronous flips for i915.

v7: -Rebased.

v8: -Rebased.

v9: -Rebased.

v10: Move all documentation changes to this patch. (Ville)

Signed-off-by: Karthik B S <karthik.b.s@intel.com>
Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200921110210.21182-8-karthik.b.s@intel.com
This commit is contained in:
Karthik B S 2020-09-21 16:32:09 +05:30 committed by Ville Syrjälä
parent e5cb1afba4
commit 6914c9685e
2 changed files with 24 additions and 0 deletions
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6
Documentation/gpu/i915.rst
View File

@ -118,6 +118,12 @@ Atomic Plane Helpers
.. kernel-doc:: drivers/gpu/drm/i915/display/intel_atomic_plane.c
:internal:
Asynchronous Page Flip
----------------------
.. kernel-doc:: drivers/gpu/drm/i915/display/intel_display.c
:doc: asynchronous flip implementation
Output Probing
--------------

18
drivers/gpu/drm/i915/display/intel_display.c
View File

@ -14929,6 +14929,24 @@ static bool intel_cpu_transcoders_need_modeset(struct intel_atomic_state *state,
return false;
}
/**
* DOC: asynchronous flip implementation
*
* Asynchronous page flip is the implementation for the DRM_MODE_PAGE_FLIP_ASYNC
* flag. Currently async flip is only supported via the drmModePageFlip IOCTL.
* Correspondingly, support is currently added for primary plane only.
*
* Async flip can only change the plane surface address, so anything else
* changing is rejected from the intel_atomic_check_async() function.
* Once this check is cleared, flip done interrupt is enabled using
* the skl_enable_flip_done() function.
*
* As soon as the surface address register is written, flip done interrupt is
* generated and the requested events are sent to the usersapce in the interrupt
* handler itself. The timestamp and sequence sent during the flip done event
* correspond to the last vblank and have no relation to the actual time when
* the flip done event was sent.
*/
static int intel_atomic_check_async(struct intel_atomic_state *state)
{
struct drm_i915_private *i915 = to_i915(state->base.dev);