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| author | Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> | 2026-05-28 10:10:48 +0300 |
|---|---|---|
| committer | Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> | 2026-06-08 09:48:42 +0300 |
| commit | cd0d23939b8775482c30ca7ab207f185aecd6555 (patch) | |
| tree | 0601c9ae1cffe47942f28ad09b86231b1740add1 /include | |
| parent | ce73a5db44e3d5f9c0c061f0868ae209b59605f1 (diff) | |
| download | linux-cd0d23939b8775482c30ca7ab207f185aecd6555.tar.gz linux-cd0d23939b8775482c30ca7ab207f185aecd6555.zip | |
drm/bridge: split hpd_mutex into two mutexes
Currently almost all bridge drivers which implement hpd_enable /
hpd_disable callbacks simply toggle the hardware registers generating
the interrupt. However, as pointed out by Jonas Karlman and Sashiko bot,
using those callbacks for enable_irq() / disable_irq() calls or
scheduling and cancelling the work can cause a AB-BA deadlock (between
hpd_mutex lock and the corresponding lock).
Split the hpd_mutex into two locks: one simply making sure that hpd_cb /
hpd_data are consistent and another one, hpd_state_mutex, making sure
that concurrent drm_bridge_hpd_enable() / drm_bridge_hpd_disable() calls
can't end up with inconsistency between hpd_cb/_data and bridge's
internal state.
Link: https://lore.kernel.org/dri-devel/9aa4bd35-bff6-4009-a959-ce31010c7b35@kwiboo.se
Link: https://sashiko.dev/#/patchset/20260513-dp-connector-hpd-v2-0-42f757bfcbf9%40oss.qualcomm.com
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://patch.msgid.link/20260528-dp-connector-hpd-v3-1-d656eb1079b7@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/drm/drm_bridge.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 4ba3a5deef9a..00a95f927e34 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -1257,6 +1257,10 @@ struct drm_bridge { */ struct mutex hpd_mutex; /** + * @hpd_state_mutex: Protects the HPD en/disablement state for the bridge. + */ + struct mutex hpd_state_mutex; + /** * @hpd_cb: Hot plug detection callback, registered with * drm_bridge_hpd_enable(). */ |