linux-kernel - [PATCH 5.15 182/201] drm/amd/display: Reset DMCUB before HW init

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Date:   Wed, 27 Jul 2022 18:11:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Aurabindo Jayamohanan Pillai <Aurabindo.Pillai@....com>,
        Pavle Kotarac <Pavle.Kotarac@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Alex Deucher <alexander.deucher@....com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>
Subject: [PATCH 5.15 182/201] drm/amd/display: Reset DMCUB before HW init

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

commit 791255ca9fbe38042cfd55df5deb116dc11fef18 upstream.

[Why]
If the firmware wasn't reset by PSP or HW and is currently running
then the firmware will hang or perform underfined behavior when we
modify its firmware state underneath it.

[How]
Reset DMCUB before setting up cache windows and performing HW init.

Reviewed-by: Aurabindo Jayamohanan Pillai <Aurabindo.Pillai@....com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Cc: "Limonciello, Mario" <Mario.Limonciello@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1028,6 +1028,11 @@ static int dm_dmub_hw_init(struct amdgpu
 		return 0;
 	}
 
+	/* Reset DMCUB if it was previously running - before we overwrite its memory. */
+	status = dmub_srv_hw_reset(dmub_srv);
+	if (status != DMUB_STATUS_OK)
+		DRM_WARN("Error resetting DMUB HW: %d\n", status);
+
 	hdr = (const struct dmcub_firmware_header_v1_0 *)dmub_fw->data;
 
 	fw_inst_const = dmub_fw->data +