This series is a v2 of patch "driver core: Disable driver deferred probe timeout by default" [0] but using a slightly different approach after the feedback I got on v1. The problem with v1 was that just disabling the probe deferral timeout by default would cause a regression for drivers that may want to probe even if their (optional) dependencies are not present yet. But this was achieved by timing out the probe deferral mechanism, which calls fw_devlink_drivers_done() in its work queue function handler. There is not reason to tie the two though, it should be possible to relax the device links to allow drivers to probe even if their optional suppliers are not present, while still keep the probe deferral mechanism enabled so that drivers that have required dependencies are still able to defer their probe. This series decouple the two operations by adding a fw_devlink.timeout= command line parameter. That way, the probe deferral timeout can be set to -1 by default, reverting to the previous behaviour while still allow drivers to probe with optional dependencies missing. Patch #1 is just a cleanup that makes the driver_deferred_probe_timeout variable static since isn't used outside of its compilation unit. Patch #2 disables the deferred probe mechanism after late_initcall if modules are disable. Since there is no point to schedule the timer in that case. Patch #3 adds the new "fw_devlink.timeout=" cmdline param, that can be used to set a timeout for the device links enforcing. The semantics are quite similar to the existing "deferred_probe_timeout=" cmdline param. Patch #4 then changes the default value for the probe deferral timeout, to just disable it by default and make the probe deferral mechanism to revert to the behaviour that had before. That is, to just try to probe the drivers indefinitely. But the device link enforcing timeout is set to 10 seconds, to keep the existing expectations for drivers that want to probe even if their optional dependencies are not present. I have tested on my HP X2 Chromebook and the DRM driver that was failing to probe before now works without any cmdline parameters. I also tested with different combinations of device links and deferred probe timeouts. [0]: https://lore.kernel.org/lkml/354820e8-939c-781a-0d76-c1574c43b7f3@xxxxxxxxxx/T/#t Best regards, Javier Changes in v2: - Mention in the commit messsage the specific machine and drivers that are affected by the issue (Greg). - Double check the commit message for accuracy (John). - Add a second workqueue to timeout the devlink enforcing and allow drivers to probe even without their optional dependencies available. Javier Martinez Canillas (4): driver core: Make driver_deferred_probe_timeout a static variable driver core: Set deferred probe timeout to 0 if modules are disabled driver core: Add fw_devlink.timeout param to stop waiting for devlinks driver core: Disable driver deferred probe timeout by default .../admin-guide/kernel-parameters.txt | 7 +++ drivers/base/dd.c | 48 +++++++++++++++---- include/linux/device/driver.h | 1 - 3 files changed, 47 insertions(+), 9 deletions(-) -- 2.38.1
