From: Fangzhi Zuo Jerry.Zuo@amd.com
[ Upstream commit cfa0904a35fd0231f4d05da0190f0a22ed881cce ]
[why] 1. With allow_0_dtb_clk enabled, the time required to latch DTBCLK to 600 MHz depends on the SMU. If DTBCLK is not latched to 600 MHz before set_mode completes, gating DTBCLK causes the DP2 sink to lose its clock source.
2. The existing DTBCLK gating sequence ungates DTBCLK based on both pix_clk and ref_dtbclk, but gates DTBCLK when either pix_clk or ref_dtbclk is zero. pix_clk can be zero outside the set_mode sequence before DTBCLK is properly latched, which can lead to DTBCLK being gated by mistake.
[how] Consider both pixel_clk and ref_dtbclk when determining when it is safe to gate DTBCLK; this is more accurate.
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4701 Fixes: 5949e7c4890c ("drm/amd/display: Enable Dynamic DTBCLK Switch") Reviewed-by: Charlene Liu charlene.liu@amd.com Reviewed-by: Aurabindo Pillai aurabindo.pillai@amd.com Signed-off-by: Fangzhi Zuo Jerry.Zuo@amd.com Signed-off-by: Roman Li roman.li@amd.com Tested-by: Dan Wheeler daniel.wheeler@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com (cherry picked from commit d04eb0c402780ca037b62a6aecf23b863545ebca) Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c | 4 +++- drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c | 2 +- 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c index 3114b3fae9eff..6e9d6090b10ff 100644 --- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c +++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn35/dcn35_clk_mgr.c @@ -377,6 +377,8 @@ void dcn35_update_clocks(struct clk_mgr *clk_mgr_base, display_count = dcn35_get_active_display_cnt_wa(dc, context, &all_active_disps); if (new_clocks->dtbclk_en && !new_clocks->ref_dtbclk_khz) new_clocks->ref_dtbclk_khz = 600000; + else if (!new_clocks->dtbclk_en && new_clocks->ref_dtbclk_khz > 590000) + new_clocks->ref_dtbclk_khz = 0;
/* * if it is safe to lower, but we are already in the lower state, we don't have to do anything @@ -418,7 +420,7 @@ void dcn35_update_clocks(struct clk_mgr *clk_mgr_base,
actual_dtbclk = REG_READ(CLK1_CLK4_CURRENT_CNT);
- if (actual_dtbclk) { + if (actual_dtbclk > 590000) { clk_mgr_base->clks.ref_dtbclk_khz = new_clocks->ref_dtbclk_khz; clk_mgr_base->clks.dtbclk_en = new_clocks->dtbclk_en; } diff --git a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c index a841eaafbaaa8..57202ef3fd985 100644 --- a/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c +++ b/drivers/gpu/drm/amd/display/dc/dccg/dcn35/dcn35_dccg.c @@ -1405,7 +1405,7 @@ static void dccg35_set_dtbclk_dto( __func__, params->otg_inst, params->pixclk_khz, params->ref_dtbclk_khz, req_dtbclk_khz, phase, modulo);
- } else { + } else if (!params->ref_dtbclk_khz && !req_dtbclk_khz) { switch (params->otg_inst) { case 0: REG_UPDATE(DCCG_GATE_DISABLE_CNTL5, DTBCLK_P0_GATE_DISABLE, 0);