[3.19.y-ckt stable] Patch "drm/radeon: retry dcpd fetch" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/radeon: retry dcpd fetch

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From a85f61c6b1fd68951dc398aec29956f52075c1dc Mon Sep 17 00:00:00 2001
From: Alex Deucher <alexander.deucher at amd.com>
Date: Mon, 18 May 2015 10:38:25 -0400
Subject: drm/radeon: retry dcpd fetch

commit 0f28d1281b6c54cc98746ae61e44e7f540758ed4 upstream.

Retry the dpcd fetch several times.  Some eDP panels
fail several times before the fetch is successful.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=73530

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/radeon/atombios_dp.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 5bf825d..ceab25d 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -405,19 +405,21 @@ bool radeon_dp_getdpcd(struct radeon_connector *radeon_connector)
 {
 	struct radeon_connector_atom_dig *dig_connector = radeon_connector->con_priv;
 	u8 msg[DP_DPCD_SIZE];
-	int ret;
+	int ret, i;

-	ret = drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_DPCD_REV, msg,
-			       DP_DPCD_SIZE);
-	if (ret > 0) {
-		memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE);
+	for (i = 0; i < 7; i++) {
+		ret = drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_DPCD_REV, msg,
+				       DP_DPCD_SIZE);
+		if (ret == DP_DPCD_SIZE) {
+			memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE);

-		DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd),
-			      dig_connector->dpcd);
+			DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd),
+				      dig_connector->dpcd);

-		radeon_dp_probe_oui(radeon_connector);
+			radeon_dp_probe_oui(radeon_connector);

-		return true;
+			return true;
+		}
 	}
 	dig_connector->dpcd[0] = 0;
 	return false;
--
1.9.1