On Thu, Dec 21, 2017 at 05:06:22PM -0800, Pandiyan, Dhinakaran wrote:
On Thu, 2017-12-21 at 10:52 -0800, Manasi Navare wrote:
On Wed, Dec 20, 2017 at 10:36:24PM -0800, Dhinakaran Pandiyan wrote:
Occasionally there are LINK_ADDRESS sideband messages timing out with the Lenovo MST dock + Dell MST monitor(w/ in-built branch) setup I have. These failures lead to the display not coming up on boot. Power cycling the port corresponding to the MST monitor's branch device and resending the message fixes the issue. I am not entirely sure if this is specific to my setup. However, as the power state is toggled conditionally on LINK_ADDRESS timeouts, this should not affect the working cases.
Cc: Lyude lyude@redhat.com Cc: Dave Airlie airlied@redhat.com Cc: Jani Nikula jani.nikula@intel.com Signed-off-by: Dhinakaran Pandiyan dhinakaran.pandiyan@intel.com
drivers/gpu/drm/drm_dp_mst_topology.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 70dcfa58d3c2..e06defcdcf18 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1596,8 +1596,9 @@ static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr, int len; struct drm_dp_sideband_msg_tx *txmsg; int ret;
- int attempts = 5;
Does the spec say this should be retried 5 times or is this just an experimental number?
The spec. does not say how many times to retry, but it does say the source is responsible for retrying.
We have such magical numbers for retries all over the DP code and that makes debugging harder later, so atleast a comment of why its 5 would help.
Takes about 22 seconds from boot to complete 5 retries on my SKL, I think that's enough trying from the kernel side before pulling out the DP cable makes sense :)
It still appears to be a magical number so better to comment it properly. Helps in the debug
- txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+retry: txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL); if (!txmsg) return;
@@ -1635,9 +1636,17 @@ static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr, } (*mgr->cbs->hotplug)(mgr); }
- } else if (attempts--) {
This should be --attempts if you want the total attempts to be 5
I don't.
Yes the variable attempts is misleading in that case. Probably call it "tries"
Manasi
Manasi
kfree(txmsg);drm_dp_send_power_updown_phy(mstb->mgr, mstb->port_parent,false);drm_dp_send_power_updown_phy(mstb->mgr, mstb->port_parent,true);DRM_DEBUG_KMS("link address failed %d, retrying\n", ret);goto retry;
DRM_DEBUG_KMS("link address failed %d\n", ret);
DRM_DEBUG_KMS("link address failed %d, giving up\n", ret);}
kfree(txmsg);
-- 2.11.0
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