From a363d80566ccb1bbc3df30c9f709df5f3af0a8ef Mon Sep 17 00:00:00 2001
From: Michael Strauss <michael.strauss@amd.com>
Date: Thu, 21 Oct 2021 13:27:16 -0400
Subject: [PATCH] drm/amd/display: Fallback to clocks which meet requested voltage on DCN31
Git-commit: 54149d13f369e1ab02f36b91feee02069184c1d8
Patch-mainline: v5.15
References: stable-5.14.16

commit 54149d13f369e1ab02f36b91feee02069184c1d8 upstream.

[WHY]
On certain configs, SMU clock table voltages don't match which cause parser
to behave incorrectly by leaving dcfclk and socclk table entries unpopulated.

[HOW]
Currently the function that finds the corresponding clock for a given voltage
only checks for exact voltage level matches. In the case that no match gets
found, parser now falls back to searching for the max clock which meets the
requested voltage (i.e. its corresponding voltage is below requested).

Signed-off-by: Michael Strauss <michael.strauss@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 .../amd/display/dc/clk_mgr/dcn31/dcn31_clk_mgr.c    | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn31/dcn31_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn31/dcn31_clk_mgr.c
index 035ba0ef6369..377c4e53a2b3 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn31/dcn31_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn31/dcn31_clk_mgr.c
@@ -518,14 +518,21 @@ static unsigned int find_clk_for_voltage(
 		unsigned int voltage)
 {
 	int i;
+	int max_voltage = 0;
+	int clock = 0;
 
 	for (i = 0; i < NUM_SOC_VOLTAGE_LEVELS; i++) {
-		if (clock_table->SocVoltage[i] == voltage)
+		if (clock_table->SocVoltage[i] == voltage) {
 			return clocks[i];
+		} else if (clock_table->SocVoltage[i] >= max_voltage &&
+				clock_table->SocVoltage[i] < voltage) {
+			max_voltage = clock_table->SocVoltage[i];
+			clock = clocks[i];
+		}
 	}
 
-	ASSERT(0);
-	return 0;
+	ASSERT(clock);
+	return clock;
 }
 
 void dcn31_clk_mgr_helper_populate_bw_params(
-- 
2.26.2