From: Sung Lee <sung.lee@xxxxxxx>
[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 <sung.lee@xxxxxxx>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@xxxxxxx>
Reviewed-by: Tony Cheng <Tony.Cheng@xxxxxxx>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
---
.../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 {
--
2.24.0
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