linux-kernel - [PATCH 5.4 047/453] drm/amd/display: Init clock value by current vbios CLKs

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Message-Id: <20201228124939.518905538@linuxfoundation.org>
Date:   Mon, 28 Dec 2020 13:44:43 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Brandon Syu <Brandon.Syu@....com>,
        Tony Cheng <Tony.Cheng@....com>,
        Aurabindo Pillai <aurabindo.pillai@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 047/453] drm/amd/display: Init clock value by current vbios CLKs

From: Brandon Syu <Brandon.Syu@....com>

[ Upstream commit 7e0b367db85ef7b91399006253759a024eab7653 ]

[Why]
While booting into OS, driver updates DPP/DISP CLKs.
But init clock value is zero which is invalid.

[How]
Get current clocks value to update init clocks.
To avoid underflow.

Signed-off-by: Brandon Syu <Brandon.Syu@....com>
Reviewed-by: Tony Cheng <Tony.Cheng@....com>
Acked-by: Aurabindo Pillai <aurabindo.pillai@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c   | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
index dd92f9c295b45..9f301f8575a54 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c
@@ -97,8 +97,17 @@ void rn_update_clocks(struct clk_mgr *clk_mgr_base,
 			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)
+	/*
+	 * Temporally ignore thew 0 cases for disp and dpp clks.
+	 * We may have a new feature that requires 0 clks in the future.
+	 */
+	if (new_clocks->dppclk_khz == 0 || new_clocks->dispclk_khz == 0) {
+		new_clocks->dppclk_khz = clk_mgr_base->clks.dppclk_khz;
+		new_clocks->dispclk_khz = clk_mgr_base->clks.dispclk_khz;
+	}
+
+	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;
 		clk_mgr_base->clks.dppclk_khz = new_clocks->dppclk_khz;
 		update_dppclk = true;
-- 
2.27.0