[PATCH 5.7 104/112] drm/amd/display: Only revalidate bandwidth on medium and fast updates

Greg Kroah-Hartman
2020-07-07T15:26:44Z

From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

commit 6eb3cf2e06d22b2b08e6b0ab48cb9c05a8e1a107 upstream.

[Why]
Changes that are fast don't require updating DLG parameters making
this call unnecessary. Considering this is an expensive call it should
not be done on every flip.

DML touches clocks, p-state support, DLG params and a few other DC
internal flags and these aren't expected during fast. A hang has been
reported with this change when called on every flip which suggests that
modifying these fields is not recommended behavior on fast updates.

[How]
Guard the validation to only happen if update type isn't FAST.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1191
Fixes: a24eaa5c51255b ("drm/amd/display: Revalidate bandwidth before commiting DC updates")
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/amd/display/dc/core/dc.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -2533,10 +2533,12 @@ void dc_commit_updates_for_stream(struct

copy_stream_update_to_stream(dc, context, stream, stream_update);

- if (!dc->res_pool->funcs->validate_bandwidth(dc, context, false)) {
- DC_ERROR("Mode validation failed for stream update!\n");
- dc_release_state(context);
- return;
+ if (update_type > UPDATE_TYPE_FAST) {
+ if (!dc->res_pool->funcs->validate_bandwidth(dc, context, false)) {
+ DC_ERROR("Mode validation failed for stream update!\n");
+ dc_release_state(context);
+ return;
+ }
}

commit_planes_for_stream(