drm/amd/display: Check null pointers before used

[WHAT & HOW]
Poniters, such as dc->clk_mgr, are null checked previously in the same
function, so Coverity warns "implies that "dc->clk_mgr" might be null".
As a result, these pointers need to be checked when used again.

This fixes 10 FORWARD_NULL issues reported by Coverity.
Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/dce110/dce110_clk_mgr.c

@@ -195,7 +195,7 @@ void dce11_pplib_apply_display_requirements(
 	 * , then change minimum memory clock based on real-time bandwidth
 	 * limitation.
 	 */
-	if ((dc->ctx->asic_id.chip_family == FAMILY_AI) &&
+	if (dc->bw_vbios && (dc->ctx->asic_id.chip_family == FAMILY_AI) &&
 	     ASICREV_IS_VEGA20_P(dc->ctx->asic_id.hw_internal_rev) && (context->stream_count >= 2)) {
 		pp_display_cfg->min_memory_clock_khz = max(pp_display_cfg->min_memory_clock_khz,
 							   (uint32_t) div64_s64(

drivers/gpu/drm/amd/display/dc/hubp/dcn10/dcn10_hubp.c

@@ -749,7 +749,8 @@ bool hubp1_is_flip_pending(struct hubp *hubp)
 	if (flip_pending)
 		return true;
 
-	if (earliest_inuse_address.grph.addr.quad_part != hubp->request_address.grph.addr.quad_part)
+	if (hubp &&
+	    earliest_inuse_address.grph.addr.quad_part != hubp->request_address.grph.addr.quad_part)
 		return true;
 
 	return false;

drivers/gpu/drm/amd/display/dc/hubp/dcn20/dcn20_hubp.c

@@ -927,7 +927,8 @@ bool hubp2_is_flip_pending(struct hubp *hubp)
 	if (flip_pending)
 		return true;
 
-	if (earliest_inuse_address.grph.addr.quad_part != hubp->request_address.grph.addr.quad_part)
+	if (hubp &&
+	    earliest_inuse_address.grph.addr.quad_part != hubp->request_address.grph.addr.quad_part)
 		return true;
 
 	return false;

drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c

@@ -949,7 +949,7 @@ void dce110_edp_backlight_control(
 {
 	struct dc_context *ctx = link->ctx;
 	struct bp_transmitter_control cntl = { 0 };
-	uint8_t pwrseq_instance;
+	uint8_t pwrseq_instance = 0;
 	unsigned int pre_T11_delay = OLED_PRE_T11_DELAY;
 	unsigned int post_T7_delay = OLED_POST_T7_DELAY;
 
@@ -1002,6 +1002,7 @@ void dce110_edp_backlight_control(
 	 */
 	/* dc_service_sleep_in_milliseconds(50); */
 		/*edp 1.2*/
+	if (link->panel_cntl)
 		pwrseq_instance = link->panel_cntl->pwrseq_inst;
 
 	if (cntl.action == TRANSMITTER_CONTROL_BACKLIGHT_ON) {

drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c

@@ -1553,7 +1553,7 @@ void dcn10_init_hw(struct dc *dc)
 		dc->clk_mgr->funcs->init_clocks(dc->clk_mgr);
 
 	/* Align bw context with hw config when system resume. */
-	if (dc->clk_mgr->clks.dispclk_khz != 0 && dc->clk_mgr->clks.dppclk_khz != 0) {
+	if (dc->clk_mgr && dc->clk_mgr->clks.dispclk_khz != 0 && dc->clk_mgr->clks.dppclk_khz != 0) {
 		dc->current_state->bw_ctx.bw.dcn.clk.dispclk_khz = dc->clk_mgr->clks.dispclk_khz;
 		dc->current_state->bw_ctx.bw.dcn.clk.dppclk_khz = dc->clk_mgr->clks.dppclk_khz;
 	}
@@ -1673,7 +1673,7 @@ void dcn10_init_hw(struct dc *dc)
 		REG_UPDATE(DCFCLK_CNTL, DCFCLK_GATE_DIS, 0);
 	}
 
-	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);
 }
 

drivers/gpu/drm/amd/display/dc/hwss/dcn31/dcn31_hwseq.c

@@ -256,10 +256,10 @@ void dcn31_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)

drivers/gpu/drm/amd/display/dc/hwss/dcn35/dcn35_hwseq.c

@@ -235,7 +235,7 @@ void dcn35_init_hw(struct dc *dc)
 	if (hws->funcs.enable_power_gating_plane)
 		hws->funcs.enable_power_gating_plane(dc->hwseq, true);
 */
-	if (res_pool->hubbub->funcs->dchubbub_init)
+	if (res_pool->hubbub && res_pool->hubbub->funcs->dchubbub_init)
 		res_pool->hubbub->funcs->dchubbub_init(dc->res_pool->hubbub);
 	/* If taking control over from VBIOS, we may want to optimize our first
 	 * mode set, so we need to skip powering down pipes until we know which
@@ -328,10 +328,10 @@ void dcn35_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);
 
 
@@ -1039,7 +1039,7 @@ void dcn35_calc_blocks_to_gate(struct dc *dc, struct dc_state *context,
 		if (pipe_ctx->plane_res.hubp)
 			update_state->pg_pipe_res_update[PG_HUBP][pipe_ctx->plane_res.hubp->inst] = false;
 
-		if (pipe_ctx->plane_res.dpp)
+		if (pipe_ctx->plane_res.dpp && pipe_ctx->plane_res.hubp)
 			update_state->pg_pipe_res_update[PG_DPP][pipe_ctx->plane_res.hubp->inst] = false;
 
 		if (pipe_ctx->plane_res.dpp || pipe_ctx->stream_res.opp)

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c

@@ -2258,7 +2258,7 @@ bool dp_verify_link_cap_with_retries(
 
 		memset(&link->verified_link_cap, 0,
 				sizeof(struct dc_link_settings));
-		if (!link_detect_connection_type(link, &type) || type == dc_connection_none) {
+		if (link->link_enc && (!link_detect_connection_type(link, &type) || type == dc_connection_none)) {
 			link->verified_link_cap = fail_safe_link_settings;
 			break;
 		} else if (dp_verify_link_cap(link, known_limit_link_setting, &fail_count)) {