diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c index d2679c5d976b066ada22dfeb9b89a5c53bdf5e84..d3570d3d573c2c9501d8a5f033f63f89231d8e2d 100644 --- a/drivers/gpu/drm/xe/xe_devcoredump.c +++ b/drivers/gpu/drm/xe/xe_devcoredump.c @@ -29,30 +29,39 @@ /** * DOC: Xe device coredump * - * Devices overview: * Xe uses dev_coredump infrastructure for exposing the crash errors in a - * standardized way. - * devcoredump exposes a temporary device under /sys/class/devcoredump/ - * which is linked with our card device directly. - * The core dump can be accessed either from - * /sys/class/drm/card<n>/device/devcoredump/ or from - * /sys/class/devcoredump/devcd<m> where - * /sys/class/devcoredump/devcd<m>/failing_device is a link to - * /sys/class/drm/card<n>/device/. + * standardized way. Once a crash occurs, devcoredump exposes a temporary + * node under ``/sys/class/devcoredump/devcd<m>/``. The same node is also + * accessible in ``/sys/class/drm/card<n>/device/devcoredump/``. The + * ``failing_device`` symlink points to the device that crashed and created the + * coredump. * - * Snapshot at hang: - * The 'data' file is printed with a drm_printer pointer at devcoredump read - * time. For this reason, we need to take snapshots from when the hang has - * happened, and not only when the user is reading the file. Otherwise the - * information is outdated since the resets might have happened in between. + * The following characteristics are observed by xe when creating a device + * coredump: * - * 'First' failure snapshot: - * In general, the first hang is the most critical one since the following hangs - * can be a consequence of the initial hang. For this reason we only take the - * snapshot of the 'first' failure and ignore subsequent calls of this function, - * at least while the coredump device is alive. Dev_coredump has a delayed work - * queue that will eventually delete the device and free all the dump - * information. + * **Snapshot at hang**: + * The 'data' file contains a snapshot of the HW and driver states at the time + * the hang happened. Due to the driver recovering from resets/crashes, it may + * not correspond to the state of the system when the file is read by + * userspace. + * + * **Coredump release**: + * After a coredump is generated, it stays in kernel memory until released by + * userpace by writing anything to it, or after an internal timer expires. The + * exact timeout may vary and should not be relied upon. Example to release + * a coredump: + * + * .. code-block:: shell + * + * $ > /sys/class/drm/card0/device/devcoredump/data + * + * **First failure only**: + * In general, the first hang is the most critical one since the following + * hangs can be a consequence of the initial hang. For this reason a snapshot + * is taken only for the first failure. Until the devcoredump is released by + * userspace or kernel, all subsequent hangs do not override the snapshot nor + * create new ones. Devcoredump has a delayed work queue that will eventually + * delete the file node and free all the dump information. */ #ifdef CONFIG_DEV_COREDUMP