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From 43235db21fc23559f50a62f8f273002eeb506f5a Mon Sep 17 00:00:00 2001
From: Aurabindo Pillai <aurabindo.pillai@amd.com>
Date: Fri, 27 Oct 2023 15:59:48 -0400
Subject: [PATCH] drm/amd/display: Fix a debugfs null pointer error
Git-commit: efb91fea652a42fcc037d2a9ef4ecd1ffc5ff4b7
Patch-mainline: v6.8-rc1
References: git-fixes

commit efb91fea652a42fcc037d2a9ef4ecd1ffc5ff4b7 upstream.

[WHY & HOW]
Check whether get_subvp_en() callback exists before calling it.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Alex Hung <alex.hung@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index 13a177d34376..45c972f2630d 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -3647,12 +3647,16 @@ static int capabilities_show(struct seq_file *m, void *unused)
 	bool mall_supported = dc->caps.mall_size_total;
 	bool subvp_supported = dc->caps.subvp_fw_processing_delay_us;
 	unsigned int mall_in_use = false;
-	unsigned int subvp_in_use = dc->cap_funcs.get_subvp_en(dc, dc->current_state);
+	unsigned int subvp_in_use = false;
+
 	struct hubbub *hubbub = dc->res_pool->hubbub;
 
 	if (hubbub->funcs->get_mall_en)
 		hubbub->funcs->get_mall_en(hubbub, &mall_in_use);
 
+	if (dc->cap_funcs.get_subvp_en)
+		subvp_in_use = dc->cap_funcs.get_subvp_en(dc, dc->current_state);
+
 	seq_printf(m, "mall supported: %s, enabled: %s\n",
 			   mall_supported ? "yes" : "no", mall_in_use ? "yes" : "no");
 	seq_printf(m, "sub-viewport supported: %s, enabled: %s\n",
-- 
2.35.3