diff mbox

[4/8] drm/i915/dp: try to read receiver capabilities 3 times when detecting

Message ID 1309558978-4704-5-git-send-email-jbarnes@virtuousgeek.org (mailing list archive)
State New, archived
Headers show

Commit Message

Jesse Barnes July 1, 2011, 10:22 p.m. UTC 
If ->detect is called too soon after a hot plug event, the sink may not
be ready yet.  So try up to 3 times with 1ms sleeps in between tries to
get the data (spec dictates that receivers must be ready to respond within
1ms and that sources should try 3 times).

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/intel_dp.c |   15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

Comments

Keith Packard July 1, 2011, 11:45 p.m. UTC | #1 
On Fri,  1 Jul 2011 15:22:54 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> If ->detect is called too soon after a hot plug event, the sink may not
> be ready yet.  So try up to 3 times with 1ms sleeps in between tries to
> get the data (spec dictates that receivers must be ready to respond within
> 1ms and that sources should try 3 times).

See previous patch comment -- the dpcd read should be stuffed into a
separate function and shared between the four current users.
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index dcef7fd..480e8d3 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1554,6 +1554,7 @@  static enum drm_connector_status
 ironlake_dp_detect(struct intel_dp *intel_dp)
 {
 	enum drm_connector_status status;
+	int ret, i;
 
 	/* Can't disconnect eDP, but you can close the lid... */
 	if (is_edp(intel_dp)) {
@@ -1564,12 +1565,16 @@  ironlake_dp_detect(struct intel_dp *intel_dp)
 	}
 
 	status = connector_status_disconnected;
-	if (intel_dp_aux_native_read(intel_dp,
-				     0x000, intel_dp->dpcd,
-				     sizeof (intel_dp->dpcd))
-	    == sizeof(intel_dp->dpcd)) {
-		if (intel_dp->dpcd[DP_DPCD_REV] != 0)
+	for (i = 0; i < 3; i++) {
+		ret = intel_dp_aux_native_read(intel_dp,
+					       0x000, intel_dp->dpcd,
+					       sizeof (intel_dp->dpcd));
+		if (ret == sizeof(intel_dp->dpcd) &&
+		    intel_dp->dpcd[DP_DPCD_REV] != 0) {
 			status = connector_status_connected;
+			break;
+		}
+		msleep(1);
 	}
 	DRM_DEBUG_KMS("DPCD: %hx%hx%hx%hx\n", intel_dp->dpcd[0],
 		      intel_dp->dpcd[1], intel_dp->dpcd[2], intel_dp->dpcd[3]);