drm/amd/display: prevent register access while in IPS

We can't read/write to DCN registers while in IPS. Since, that can cause
the system to hang. So, before proceeding with the access in that
scenario, force the system out of IPS.

Cc: [e-mail] # 6.6+
Reviewed-by: Roman Li <[e-mail]>
Signed-off-by: Hamza Mahfooz <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

···
 	mutex_unlock(&adev->dm.dc_lock);
 }
 
+static inline void amdgpu_dm_exit_ips_for_hw_access(struct dc *dc)
+{
+	if (dc->ctx->dmub_srv && !dc->ctx->dmub_srv->idle_exit_counter)
+		dc_exit_ips_for_hw_access(dc);
+}
+
 void dm_write_reg_func(const struct dc_context *ctx, uint32_t address,
 		       u32 value, const char *func_name)
 {
···
 		return;
 	}
 #endif
+
+	amdgpu_dm_exit_ips_for_hw_access(ctx->dc);
 	cgs_write_register(ctx->cgs_device, address, value);
 	trace_amdgpu_dc_wreg(&ctx->perf_trace->write_count, address, value);
 }
···
 		ASSERT(false);
 		return 0;
 	}
+
+	amdgpu_dm_exit_ips_for_hw_access(ctx->dc);
 
 	value = cgs_read_register(ctx->cgs_device, address);