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drm/amd/display: add explanation for surface_update_type

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Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Dmytro Laktyushkin 2017-05-10 18:24:24 -04:00 committed by Alex Deucher
parent b71a061801
commit 81e2b2de3d
1 changed files with 27 additions and 1 deletions
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28
drivers/gpu/drm/amd/display/dc/dc.h
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@ -434,9 +434,35 @@ bool dc_post_update_surfaces_to_stream(
void dc_update_surfaces_for_stream(struct dc *dc, struct dc_surface_update *updates,
int surface_count, const struct dc_stream *stream);
/* Surface update type is used by dc_update_surfaces_and_stream
* The update type is determined at the very beginning of the function based
* on parameters passed in and decides how much programming (or updating) is
* going to be done during the call.
*
* UPDATE_TYPE_FAST is used for really fast updates that do not require much
* logical calculations or hardware register programming. This update MUST be
* ISR safe on windows. Currently fast update will only be used to flip surface
* address.
*
* UPDATE_TYPE_MED is used for slower updates which require significant hw
* re-programming however do not affect bandwidth consumption or clock
* requirements. At present, this is the level at which front end updates
* that do not require us to run bw_calcs happen. These are in/out transfer func
* updates, viewport offset changes, recout size changes and pixel depth changes.
* This update can be done at ISR, but we want to minimize how often this happens.
*
* UPDATE_TYPE_FULL is slow. Really slow. This requires us to recalculate our
* bandwidth and clocks, possibly rearrange some pipes and reprogram anything front
* end related. Any time viewport dimensions, recout dimensions, scaling ratios or
* gamma need to be adjusted or pipe needs to be turned on (or disconnected) we do
* a full update. This cannot be done at ISR level and should be a rare event.
* Unless someone is stress testing mpo enter/exit, playing with colour or adjusting
* underscan we don't expect to see this call at all.
*/
enum surface_update_type {
UPDATE_TYPE_FAST, /* super fast, safe to execute in isr */
UPDATE_TYPE_MED, /* a lot of programming needed. may need to alloc */
UPDATE_TYPE_MED, /* ISR safe, most of programming needed, no bw/clk change*/
UPDATE_TYPE_FULL, /* may need to shuffle resources */
};