On Thu, Jun 29, 2017 at 11:33 AM, Maarten Lankhorst maarten.lankhorst@linux.intel.com wrote:
Op 29-06-17 om 11:23 schreef Daniel Vetter:
On Thu, Jun 29, 2017 at 11:10 AM, Maarten Lankhorst maarten.lankhorst@linux.intel.com wrote:
Op 27-06-17 om 16:59 schreef Daniel Vetter:
From: Thierry Reding treding@nvidia.com
Move the modeset locking from drivers into FB helpers.
v2: Also handle intel_connector_add_to_fbdev.
Tested-by: John Stultz john.stultz@linaro.org Signed-off-by: Thierry Reding treding@nvidia.com (v1) Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/drm_fb_helper.c | 40 +++++++++++++++++++++++++++++----- drivers/gpu/drm/i915/intel_dp_mst.c | 6 ----- drivers/gpu/drm/radeon/radeon_dp_mst.c | 7 ------ 3 files changed, 34 insertions(+), 19 deletions(-)
I know we suck at DP-MST. But I fear the unregister leaves open a race with mst_port being unset without connection_mutex..
best_encoder() and mode_valid() appear to use it. It's probably harmless and I have no good solution, so maybe just annotate it in the patch? Might also affect i915_hpd_poll_init_work, though I think the race in itself is harmless.
Hm, but this did race even before that already ... Should I just wrap the mst_port = NULL in the connection_mutex? With a big warning that we should have proper refcounting for this instead (both connectors and all the mst things are refcounted already). -Daniel
I think leave open the race, the DP-MST modeset code itself doesn't use the connector->mst_port, just the detect callbacks do. In case of nonblocking modeset mst_port might already fall away so it's not like the race is any worse now.
I don't even know how to solve it, except by not unplugging. :)
Why does grabbing the lock not fix the race? ->detect eventually calls drm_dp_get_validated_port_ref, which will bail on a zombie mst port.. -Daniel