drm/amd/display: fix up reference clock abstractions

[why]
"reference clock" is a very overloaded variable in DC and causes confusion
as there are multiple sources of reference clock, which may be different values
incorrect input values to DML will cause DCHUB to be programmed improperly
and lead to hard to debug underflow issues

[how]
instead of using ref clock everywhere, specify WHICH ref clock:
- xtalin
- dccg refclk
- dchub refclk

these are all distinct values which may not be equal

Signed-off-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: David Francis <David.Francis@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/inc/hw/dchubbub.h b/drivers/gpu/drm/amd/display/dc/inc/hw/dchubbub.h
index 9d2d8e51306c..5e8fead3c09a 100644
--- a/drivers/gpu/drm/amd/display/dc/inc/hw/dchubbub.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/hw/dchubbub.h
@@ -73,6 +73,10 @@ struct hubbub_funcs {
 
 	void (*wm_read_state)(struct hubbub *hubbub,
 			struct dcn_hubbub_wm *wm);
+
+	void (*get_dchub_ref_freq)(struct hubbub *hubbub,
+			unsigned int dccg_ref_freq_inKhz,
+			unsigned int *dchub_ref_freq_inKhz);
 };
 
 struct hubbub {