[PATCH 5.15 184/201] drm/amd/display: Fix surface optimization regression on Carrizo

Greg Kroah-Hartman
2022-07-27T17:22:57Z

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

commit 62e5a7e2333a9f5395f6a9db766b7b06c949fe7a upstream.

[Why]
DCE legacy optimization path isn't well tested under new DC optimization
flow which can result in underflow occuring when initializing X11 on
Carrizo.

[How]
Retain the legacy optimization flow for DCE and keep the new one for DCN
to satisfy optimizations being correctly applied for ASIC that can
support it.

Fixes: 34316c1e561db0 ("drm/amd/display: Optimize bandwidth on following fast update")
Reported-by: Tom St Denis <tom.stdenis@amd.com>
Tested-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Mario Limonciello <Mario.Limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/amd/display/dc/core/dc.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -2979,8 +2979,13 @@ void dc_commit_updates_for_stream(struct
if (new_pipe->plane_state && new_pipe->plane_state != old_pipe->plane_state)
new_pipe->plane_state->force_full_update = true;
}
- } else if (update_type == UPDATE_TYPE_FAST) {
- /* Previous frame finished and HW is ready for optimization. */
+ } else if (update_type == UPDATE_TYPE_FAST && dc_ctx->dce_version >= DCE_VERSION_MAX) {
+ /*
+ * Previous frame finished and HW is ready for optimization.
+ *
+ * Only relevant for DCN behavior where we can guarantee the optimization
+ * is safe to apply - retain the legacy behavior for DCE.
+ */
dc_post_update_surfaces_to_stream(dc);
}

@@ -3039,6 +3044,12 @@ void dc_commit_updates_for_stream(struct
}
}

+ /* Legacy optimization path for DCE. */
+ if (update_type >= UPDATE_TYPE_FULL && dc_ctx->dce_version < DCE_VERSION_MAX) {
+ dc_post_update_surfaces_to_stream(dc);
+ TRACE_DCE_CLOCK_STATE(&context->bw_ctx.bw.dce);
+ }
+
return;

}