drm/i915/mst: Do not retrain new links

Browse source

The short pulse handler checks if channel equalization is okay and
goes onto retrain a link if there are active MST links. This retraining
path is not meant for new MST connections, but due to a bug elsewhere, if
active_mst_links is < 0 the boolean check for active_mst_links passes and
we proceed to retrain a new link. This results in a sequence of failed link
training attempts, most likely due to the hardware not setup for link
training at that point i.e., missing the DDI pre_enable sequence.

[   80.301272] [drm:intel_dp_check_mst_status] channel EQ not ok, retraining
[   80.301312] [drm:intel_ddi_prepare_link_retrain] *ERROR* Timeout waiting for DDI BUF C idle bit

The above error gives us a hint something went wrong before link
training started.

Check for a positive value of active_mst_links and throw in a warning for
invalid active_mst_links as debug aid.

Cc: Nathan Ciobanu <nathan.d.ciobanu@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Tested-by: Nathan Ciobanu <nathan.d.ciobanu@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180718171943.3246-1-dhinakaran.pandiyan@intel.com

...

This commit is contained in:

Dhinakaran Pandiyan 2018-07-18 10:19:42 -07:00

parent bc334d914e

commit 45ef40aab7

1 changed files with 3 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

4

drivers/gpu/drm/i915/intel_dp.c

View file