From be6ccdf861de048833b2000d80db800ab4f8d81b Mon Sep 17 00:00:00 2001 From: Alvin Lee Date: Tue, 14 Jul 2020 15:06:40 -0400 Subject: [PATCH] drm/amd/display: Don't compare dppclk before updating DTO [Why] In dcn3_update_clocks there are situations where dppclk is not lowered (i.e. stays the same), but DTO still needs to be increased before we program pipe frontend (i.e. in prepare_bandwidth). If we don't program the new DTO value before we program the pipe, we will underflow as soon as the pipe lock is released until the next call to dcn3_update_clocks where the DTO is updated. [How] Remove dppclk check before programming new DTO value. Signed-off-by: Alvin Lee Reviewed-by: Jun Lei Acked-by: Eryk Brol Signed-off-by: Alex Deucher --- .../gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c index d8af56a58196..b0e9b0509568 100644 --- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c +++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn30/dcn30_clk_mgr.c @@ -323,9 +323,10 @@ static void dcn3_update_clocks(struct clk_mgr *clk_mgr_base, /* if clock is being raised, increase refclk before lowering DTO */ if (update_dppclk || update_dispclk) dcn20_update_clocks_update_dentist(clk_mgr); - /* always update dtos unless clock is lowered and not safe to lower */ - if (new_clocks->dppclk_khz >= dc->current_state->bw_ctx.bw.dcn.clk.dppclk_khz) - dcn20_update_clocks_update_dpp_dto(clk_mgr, context, safe_to_lower); + /* There is a check inside dcn20_update_clocks_update_dpp_dto which ensures + * that we do not lower dto when it is not safe to lower. We do not need to + * compare the current and new dppclk before calling this function.*/ + dcn20_update_clocks_update_dpp_dto(clk_mgr, context, safe_to_lower); } } -- 2.34.1