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drm/amd/display: Limit minimum DPPCLK to 100MHz. 

[ Upstream commit 6c81917a04 ]

[Why]
Underflow is observed when plug in a 4K@60 monitor with
1366x768 eDP due to DPPCLK is too low.

[How]
Limit minimum DPPCLK to 100MHz.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Yongqiang Sun 2020-01-23 16:30:15 -05:00 committed by Greg Kroah-Hartman
parent 2e5154923c
commit 147fcd07ce
1 changed files with 6 additions and 0 deletions
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6
drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
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@ -91,6 +91,12 @@ void rn_update_clocks(struct clk_mgr *clk_mgr_base,
rn_vbios_smu_set_min_deep_sleep_dcfclk(clk_mgr, clk_mgr_base->clks.dcfclk_deep_sleep_khz);
}
// workaround: Limit dppclk to 100Mhz to avoid lower eDP panel switch to plus 4K monitor underflow.
if (!IS_DIAG_DC(dc->ctx->dce_environment)) {
if (new_clocks->dppclk_khz < 100000)
new_clocks->dppclk_khz = 100000;
}
if (should_set_clock(safe_to_lower, new_clocks->dppclk_khz, clk_mgr->base.clks.dppclk_khz)) {
if (clk_mgr->base.clks.dppclk_khz > new_clocks->dppclk_khz)
dpp_clock_lowered = true;