drm/amd/display: Do DIO FIFO enable after DP video stream enable

[Why]
Avoids a race condition where DIO FIFO can underflow due to no incoming
data available.

[How]
Shift the FIFO enable below stream enable.

Make sure fullness level is written before the DIO reset takes place
and that we're not doing it twice.
Reviewed-by: Syed Hassan <Syed.Hassan@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@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/dcn314/dcn314_dio_stream_encoder.c

@@ -56,7 +56,8 @@ static void enc314_enable_fifo(struct stream_encoder *enc)
 
 	/* TODO: Confirm if we need to wait for DIG_SYMCLK_FE_ON */
 	REG_WAIT(DIG_FE_CNTL, DIG_SYMCLK_FE_ON, 1, 10, 5000);
-	REG_UPDATE_2(DIG_FIFO_CTRL0, DIG_FIFO_RESET, 1, DIG_FIFO_READ_START_LEVEL, 0x7);
+	REG_UPDATE(DIG_FIFO_CTRL0, DIG_FIFO_READ_START_LEVEL, 0x7);
+	REG_UPDATE(DIG_FIFO_CTRL0, DIG_FIFO_RESET, 1);
 	REG_WAIT(DIG_FIFO_CTRL0, DIG_FIFO_RESET_DONE, 1, 10, 5000);
 	REG_UPDATE(DIG_FIFO_CTRL0, DIG_FIFO_RESET, 0);
 	REG_WAIT(DIG_FIFO_CTRL0, DIG_FIFO_RESET_DONE, 0, 10, 5000);
@@ -316,15 +317,11 @@ static void enc314_stream_encoder_dp_unblank(
 	/* switch DP encoder to CRTC data, but reset it the fifo first. It may happen
 	 * that it overflows during mode transition, and sometimes doesn't recover.
 	 */
-	REG_UPDATE(DIG_FIFO_CTRL0, DIG_FIFO_READ_START_LEVEL, 0x7);
 	REG_UPDATE(DP_STEER_FIFO, DP_STEER_FIFO_RESET, 1);
 	udelay(10);
 
 	REG_UPDATE(DP_STEER_FIFO, DP_STEER_FIFO_RESET, 0);
 
-	/* DIG Resync FIFO now needs to be explicitly enabled. */
-	enc314_enable_fifo(enc);
-
 	/* wait 100us for DIG/DP logic to prime
 	 * (i.e. a few video lines)
 	 */
@@ -340,6 +337,12 @@ static void enc314_stream_encoder_dp_unblank(
 
 	REG_UPDATE(DP_VID_STREAM_CNTL, DP_VID_STREAM_ENABLE, true);
 
+	/*
+	 * DIG Resync FIFO now needs to be explicitly enabled.
+	 * This should come after DP_VID_STREAM_ENABLE per HW docs.
+	 */
+	enc314_enable_fifo(enc);
+
 	dp_source_sequence_trace(link, DPCD_SOURCE_SEQ_AFTER_ENABLE_DP_VID_STREAM);
 }