[PATCH] drm/amd/display: Add NULL check for clk_mgr in dcn401_init_hw

[Srinivasan Shanmugam]

This commit addresses a potential null pointer dereference issue in the
`dcn401_init_hw` function. The issue could occur when `dc->clk_mgr` is
null.

The fix adds a check to ensure `dc->clk_mgr` is not null before
accessing its functions. This prevents a potential null pointer
dereference.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn401/dcn401_hwseq.c:416 dcn401_init_hw() error: we previously assumed 'dc->clk_mgr' could be null (see line 225)

Cc: Tom Chung <chiahsuan.chung at amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
Cc: Roman Li <roman.li at amd.com>
Cc: Alex Hung <alex.hung at amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai at amd.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---
 .../gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c    | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
index f4c1547a368f..16ffb41abc6d 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
@@ -413,10 +413,11 @@ void dcn401_init_hw(struct dc *dc)
 	if (!dcb->funcs->is_accelerated_mode(dcb) && dc->res_pool->hubbub->funcs->init_watermarks)
 		dc->res_pool->hubbub->funcs->init_watermarks(dc->res_pool->hubbub);
 
-	if (dc->clk_mgr->funcs->notify_wm_ranges)
+	if (dc->clk_mgr && dc->clk_mgr->funcs->notify_wm_ranges)
 		dc->clk_mgr->funcs->notify_wm_ranges(dc->clk_mgr);
 
-	if (dc->clk_mgr->funcs->set_hard_max_memclk && !dc->clk_mgr->dc_mode_softmax_enabled)
+	if (dc->clk_mgr && dc->clk_mgr->funcs->set_hard_max_memclk &&
+	    !dc->clk_mgr->dc_mode_softmax_enabled)
 		dc->clk_mgr->funcs->set_hard_max_memclk(dc->clk_mgr);
 
 	if (dc->res_pool->hubbub->funcs->force_pstate_change_control)
@@ -438,7 +439,9 @@ void dcn401_init_hw(struct dc *dc)
 		dc->debug.fams2_config.bits.enable &= dc->ctx->dmub_srv->dmub->feature_caps.fw_assisted_mclk_switch_ver == 2;
 		if (!dc->debug.fams2_config.bits.enable && dc->res_pool->funcs->update_bw_bounding_box) {
 			/* update bounding box if FAMS2 disabled */
-			dc->res_pool->funcs->update_bw_bounding_box(dc, dc->clk_mgr->bw_params);
+			if (dc->clk_mgr)
+				dc->res_pool->funcs->update_bw_bounding_box(dc,
+									    dc->clk_mgr->bw_params);
 		}
 	}
 }
-- 
2.34.1