From 760ef473f2fccdf8ca9bc0773960e16d4ce6f3d2 Mon Sep 17 00:00:00 2001 From: Sung Lee Date: Thu, 5 Dec 2019 11:58:20 -0500 Subject: [PATCH] drm/amd/display: Formula refactor for calculating DPP CLK DTO [Why] Previous formula for calculating DPP CLK DTO was hard to understand. [How] Replace with easier to understand formula that produces same results. Signed-off-by: Sung Lee Reviewed-by: Dmytro Laktyushkin Reviewed-by: Tony Cheng Acked-by: Rodrigo Siqueira Signed-off-by: Alex Deucher --- .../gpu/drm/amd/display/dc/dcn20/dcn20_dccg.c | 20 +++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.c index 1e1151356e60..50bffbfdd394 100644 --- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.c +++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.c @@ -50,20 +50,20 @@ void dccg2_update_dpp_dto(struct dccg *dccg, int dpp_inst, int req_dppclk) if (dccg->ref_dppclk && req_dppclk) { int ref_dppclk = dccg->ref_dppclk; + int modulo, phase; - ASSERT(req_dppclk <= ref_dppclk); - /* need to clamp to 8 bits */ - if (ref_dppclk > 0xff) { - int divider = (ref_dppclk + 0xfe) / 0xff; + // phase / modulo = dpp pipe clk / dpp global clk + modulo = 0xff; // use FF at the end + phase = ((modulo * req_dppclk) + ref_dppclk - 1) / ref_dppclk; - ref_dppclk /= divider; - req_dppclk = (req_dppclk + divider - 1) / divider; - if (req_dppclk > ref_dppclk) - req_dppclk = ref_dppclk; + if (phase > 0xff) { + ASSERT(false); + phase = 0xff; } + REG_SET_2(DPPCLK_DTO_PARAM[dpp_inst], 0, - DPPCLK0_DTO_PHASE, req_dppclk, - DPPCLK0_DTO_MODULO, ref_dppclk); + DPPCLK0_DTO_PHASE, phase, + DPPCLK0_DTO_MODULO, modulo); REG_UPDATE(DPPCLK_DTO_CTRL, DPPCLK_DTO_ENABLE[dpp_inst], 1); } else { -- 2.45.2