drm/amd/display: add support for DTO genarated dscclk

Current implementation will choose to use refclk as dscclk. This is not
recommended by hardware team as refclk is a fixed value which could
cause unnecessary power consumption or it could be not enough for large
DSC timings. So we are adding new interfaces so we could switch to use
dynamically generated DSCCLK by DTO. So DSCCLK is programmable based on
current pixel clock and dispclk.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Chaitanya Dhere <chaitanya.dhere@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 26 insertions, 1 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
index b16b2e14312e..5fe8b4871c77 100644
--- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
+++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
@@ -776,10 +776,26 @@ static bool dp_set_dsc_on_rx(struct pipe_ctx *pipe_ctx, bool enable)
  */
 void link_set_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)
 {
+	/* TODO: Move this to HWSS as this is hardware programming sequence not a
+	 * link layer sequence
+	 */
 	struct display_stream_compressor *dsc = pipe_ctx->stream_res.dsc;
+	struct dc *dc = pipe_ctx->stream->ctx->dc;
 	struct dc_stream_state *stream = pipe_ctx->stream;
 	struct pipe_ctx *odm_pipe;
 	int opp_cnt = 1;
+	struct dccg *dccg = dc->res_pool->dccg;
+	/* It has been found that when DSCCLK is lower than 16Mhz, we will get DCN
+	 * register access hung. When DSCCLk is based on refclk, DSCCLk is always a
+	 * fixed value higher than 16Mhz so the issue doesn't occur. When DSCCLK is
+	 * generated by DTO, DSCCLK would be based on 1/3 dispclk. For small timings
+	 * with DSC such as 480p60Hz, the dispclk could be low enough to trigger
+	 * this problem. We are implementing a workaround here to keep using dscclk
+	 * based on fixed value refclk when timing is smaller than 3x16Mhz (i.e
+	 * 48Mhz) pixel clock to avoid hitting this problem.
+	 */
+	bool should_use_dto_dscclk = (dccg->funcs->set_dto_dscclk != NULL) &&
+			stream->timing.pix_clk_100hz > 480000;
 	DC_LOGGER_INIT(dsc->ctx->logger);
 
 	for (odm_pipe = pipe_ctx->next_odm_pipe; odm_pipe; odm_pipe = odm_pipe->next_odm_pipe)
@@ -802,11 +818,15 @@ void link_set_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)
 
 		dsc->funcs->dsc_set_config(dsc, &dsc_cfg, &dsc_optc_cfg);
 		dsc->funcs->dsc_enable(dsc, pipe_ctx->stream_res.opp->inst);
+		if (should_use_dto_dscclk)
+			dccg->funcs->set_dto_dscclk(dccg, dsc->inst);
 		for (odm_pipe = pipe_ctx->next_odm_pipe; odm_pipe; odm_pipe = odm_pipe->next_odm_pipe) {
 			struct display_stream_compressor *odm_dsc = odm_pipe->stream_res.dsc;
 
 			odm_dsc->funcs->dsc_set_config(odm_dsc, &dsc_cfg, &dsc_optc_cfg);
 			odm_dsc->funcs->dsc_enable(odm_dsc, odm_pipe->stream_res.opp->inst);
+			if (should_use_dto_dscclk)
+				dccg->funcs->set_dto_dscclk(dccg, odm_dsc->inst);
 		}
 		dsc_cfg.dc_dsc_cfg.num_slices_h *= opp_cnt;
 		dsc_cfg.pic_width *= opp_cnt;
@@ -856,9 +876,14 @@ void link_set_dsc_on_stream(struct pipe_ctx *pipe_ctx, bool enable)
 		}
 
 		/* disable DSC block */
+		if (dccg->funcs->set_ref_dscclk)
+			dccg->funcs->set_ref_dscclk(dccg, pipe_ctx->stream_res.dsc->inst);
 		pipe_ctx->stream_res.dsc->funcs->dsc_disable(pipe_ctx->stream_res.dsc);
-		for (odm_pipe = pipe_ctx->next_odm_pipe; odm_pipe; odm_pipe = odm_pipe->next_odm_pipe)
+		for (odm_pipe = pipe_ctx->next_odm_pipe; odm_pipe; odm_pipe = odm_pipe->next_odm_pipe) {
+			if (dccg->funcs->set_ref_dscclk)
+				dccg->funcs->set_ref_dscclk(dccg, odm_pipe->stream_res.dsc->inst);
 			odm_pipe->stream_res.dsc->funcs->dsc_disable(odm_pipe->stream_res.dsc);
+		}
 	}
 }