From 1210b17dd4ece454d68a9283f391e3b036aeb010 Mon Sep 17 00:00:00 2001
From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Date: Sun, 23 Jan 2022 13:20:02 -0500
Subject: drm/amd/display: Only set PSR version when valid

From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

commit 1210b17dd4ece454d68a9283f391e3b036aeb010 upstream.

[Why]
DMCUB will hang if we send a PSR unsupported set version command.

This can occur if we fall-through into the default case in the switch
statement for PSR version.

[How]
Add an unsupported check after the switch statement.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: "Limonciello, Mario" <Mario.Limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c
@@ -138,6 +138,10 @@ static bool dmub_psr_set_version(struct
 		cmd.psr_set_version.psr_set_version_data.version = PSR_VERSION_UNSUPPORTED;
 		break;
 	}
+
+	if (cmd.psr_set_version.psr_set_version_data.version == PSR_VERSION_UNSUPPORTED)
+		return false;
+
 	cmd.psr_set_version.psr_set_version_data.cmd_version = DMUB_CMD_PSR_CONTROL_VERSION_1;
 	cmd.psr_set_version.psr_set_version_data.panel_inst = panel_inst;
 	cmd.psr_set_version.header.payload_bytes = sizeof(struct dmub_cmd_psr_set_version_data);