During driver probe, DMC firmware is loaded asynchronously via a
workqueue. There is a race between parse_dmc_fw() setting the payload
pointer (making has_dmc_id_fw() return true) and intel_dmc_load_program()
writing the firmware to hardware registers. If the probe thread calls
intel_dmc_enable_pipe() -> assert_dmc_loaded() in this window via
intel_modeset_setup_hw_state(), it sees parsed payload but stale HW
registers, triggering a ~20% intermittent WARNING on ADL-N warm boot.
v2: Fix by calling intel_dmc_wait_fw_load() in
intel_modeset_setup_hw_state() before iterating the CRTCs (Gustavo
Sousa).
v3: Move intel_dmc_wait_fw_load() into intel_dmc_enable_pipe() itself
so the function is self-contained (Jani Nikula, Gustavo Sousa).
Fixes: 3af2ff0840be ("drm/i915: Enable a PIPEDMC whenever its corresponding
pipe is enabled")
Signed-off-by: James Xiong <[email protected]>
Reviewed-by: Gustavo Sousa <[email protected]>
---
drivers/gpu/drm/i915/display/intel_dmc.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c
b/drivers/gpu/drm/i915/display/intel_dmc.c
index 0df4f42ba3e3..4151eae92744 100644
--- a/drivers/gpu/drm/i915/display/intel_dmc.c
+++ b/drivers/gpu/drm/i915/display/intel_dmc.c
@@ -786,7 +786,12 @@ void intel_dmc_enable_pipe(const struct intel_crtc_state
*crtc_state)
enum pipe pipe = crtc->pipe;
enum intel_dmc_id dmc_id = PIPE_TO_DMC_ID(pipe);
- if (!is_valid_dmc_id(dmc_id) || !has_dmc_id_fw(display, dmc_id))
+ if (!is_valid_dmc_id(dmc_id))
+ return;
+
+ intel_dmc_wait_fw_load(display);
+
+ if (!has_dmc_id_fw(display, dmc_id))
return;
if (!can_enable_pipedmc(crtc_state)) {
--
2.34.1
