drm/amd/display: Retry getting PSR state if command times out

[Why]
GPINT command to get PSR state from FW times out.

[How]
Add retry to get valid PSR state.
Signed-off-by: Wyatt Wood <wyatt.wood@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dc_types.h

@@ -687,7 +687,8 @@ enum dc_psr_state {
 	PSR_STATE5,
 	PSR_STATE5a,
 	PSR_STATE5b,
-	PSR_STATE5c
+	PSR_STATE5c,
+	PSR_STATE_INVALID = 0xFF
 };
 
 struct psr_config {

drivers/gpu/drm/amd/display/dc/dce/dmub_psr.c

@@ -80,9 +80,11 @@ static enum dc_psr_state convert_psr_state(uint32_t raw_state)
 static void dmub_psr_get_state(struct dmub_psr *dmub, enum dc_psr_state *state)
 {
 	struct dmub_srv *srv = dmub->ctx->dmub_srv->dmub;
-	uint32_t raw_state;
+	uint32_t raw_state = 0;
+	uint32_t retry_count = 0;
 	enum dmub_status status;
 
+	do {
 		// Send gpint command and wait for ack
 		status = dmub_srv_send_gpint_command(srv, DMUB_GPINT__GET_PSR_STATE, 0, 30);
 
@@ -92,7 +94,12 @@ static void dmub_psr_get_state(struct dmub_psr *dmub, enum dc_psr_state *state)
 			*state = convert_psr_state(raw_state);
 		} else
 			// Return invalid state when GPINT times out
-		*state = 0xFF;
+			*state = PSR_STATE_INVALID;
+
+		// Assert if max retry hit
+		if (retry_count >= 1000)
+			ASSERT(0);
+	} while (++retry_count <= 1000 && *state == PSR_STATE_INVALID);
 }
 
 /*