drm/amd/display: Expand documentation for timing

The timing programming inside DCN is far from trivial, it has multiple
parameters associated with that, and the lack of documentation does not
help comprehend this already complicated topic. This commit tries to
improve this situation by expanding the documentation of dc_crtc_timing
and the VTG program function.

Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c
index 1b796f2a84d7..cdb6e2f220f4 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c
@@ -312,6 +312,20 @@ void optc1_program_timing(
 	}
 }
 
+/**
+ * optc1_set_vtg_params - Set Vertical Timing Generator (VTG) parameters
+ *
+ * @optc: timing_generator struct used to extract the optc parameters
+ * @dc_crtc_timing: Timing parameters configured
+ * @program_fp2: Boolean value indicating if FP2 will be programmed or not
+ *
+ * OTG is responsible for generating the global sync signals, including
+ * vertical timing information for each HUBP in the dcfclk domain. Each VTG is
+ * associated with one OTG that provides HUBP with vertical timing information
+ * (i.e., there is 1:1 correspondence between OTG and VTG). This function is
+ * responsible for setting the OTG parameters to the VTG during the pipe
+ * programming.
+ */
 void optc1_set_vtg_params(struct timing_generator *optc,
 		const struct dc_crtc_timing *dc_crtc_timing, bool program_fp2)
 {