linux-kernel - [30/38] drm/radeon/kms: retry aux transactions if there are status flags

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Message-Id: <20111011165712.936325301@pistachio.kroah.org>
Date:	Tue, 11 Oct 2011 10:55:40 -0600
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Alex Deucher <alexander.deucher@....com>,
	Dave Airlie <airlied@...hat.com>
Subject: [30/38] drm/radeon/kms: retry aux transactions if there are status flags

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Alex Deucher <alexander.deucher@....com>

commit 4f332844cc87c5f99c5300f788abbe8a8c731390 upstream.

If there are error flags in the aux status, retry the transaction.
This makes aux much more reliable, especially on llano systems.

Signed-off-by: Alex Deucher <alexander.deucher@....com>
Reviewed-by: Michel Dänzer <michel.daenzer@....com>
Signed-off-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/gpu/drm/radeon/atombios_dp.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -129,7 +129,9 @@ static int radeon_dp_aux_native_write(st
 	for (retry = 0; retry < 4; retry++) {
 		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
 					    msg, msg_bytes, NULL, 0, delay, &ack);
-		if (ret < 0)
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0)
 			return ret;
 		if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
 			return send_bytes;
@@ -160,7 +162,9 @@ static int radeon_dp_aux_native_read(str
 	for (retry = 0; retry < 4; retry++) {
 		ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
 					    msg, msg_bytes, recv, recv_bytes, delay, &ack);
-		if (ret < 0)
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0)
 			return ret;
 		if ((ack & AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
 			return ret;
@@ -236,7 +240,9 @@ int radeon_dp_i2c_aux_ch(struct i2c_adap
 	for (retry = 0; retry < 4; retry++) {
 		ret = radeon_process_aux_ch(auxch,
 					    msg, msg_bytes, reply, reply_bytes, 0, &ack);
-		if (ret < 0) {
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0) {
 			DRM_DEBUG_KMS("aux_ch failed %d\n", ret);
 			return ret;
 		}


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