From 109bc10d30f33e84f1d7289f0039e0c858ade82f Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher@amd.com>
Date: Mon, 3 Oct 2011 09:13:45 -0400
Subject: [PATCH] drm/radeon/kms: fix regression in DP aux defer handling

An incorrect ordering in the error checking code lead
to DP aux defer being skipped in the aux native write
path.  Move the bytes transferred check (ret == 0)
below the defer check.

Tracked down by: Brad Campbell <brad@fnarfbargle.com>

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=41121

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Brad Campbell <brad@fnarfbargle.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/radeon/atombios_dp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 7ad43c6b1db76..f526fa77e3202 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -158,14 +158,14 @@ static int radeon_dp_aux_native_read(struct radeon_connector *radeon_connector,
 	while (1) {
 		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
 					    msg, msg_bytes, recv, recv_bytes, delay, &ack);
-		if (ret == 0)
-			return -EPROTO;
 		if (ret < 0)
 			return ret;
 		if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
 			return ret;
 		else if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
 			udelay(400);
+		else if (ret == 0)
+			return -EPROTO;
 		else
 			return -EIO;
 	}
-- 
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