dd: Invoke one probe retry cycle after some initcall levels
PATCH 1/1 dd: Invoke one probe retry cycle after some initcall levels
Drivers that are registered at an initcall level may have to wait until late_init before the probe deferral mechanism can retry their probe functions. It is possible that their dependencies were resolved much earlier, in some cases even before the next initcall level. Invoke one probe retry cycle at every _sync initcall level after subsys initcall, allowing these drivers to be probed earlier.
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To give an example many Qualcomm drivers are dependent on the regulator and bus driver. Both the regulator and bus driver are probed in the subsys_initcall level. Now the probe of bus driver requires regulator to be working. If the probe of bus driver happens before regulator, then bus driver's probe will be deferred and all other device's probes which depend on bus driver will also be deferred.
The impact of this problem is reduced if we have this patch.
Changes since v0:
* Remove arch_initcall_sync(deferred_probe_initcall) from patch. This is not really needed as none of the devices are re-probed in arch_initcall_sync level.
drivers/base/dd.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-)
drivers/base/dd.c +26 -6
@@ -224,23 +224,43 @@ void device_unblock_probing(void)driver_deferred_probe_trigger (); } +static void enable_trigger_defer_cycle (void ) +{ + driver_deferred_probe_enable = true; +driver_deferred_probe_trigger (); +/* +* Sort as many dependencies as possible before the next initcall +* level +*/ +flush_work (&deferred_probe_work); +} +/** * deferred_probe_initcall() - Enable probing of deferred devices * * We don't want to get in the way when the bulk of drivers are getting probed. * Instead, this initcall makes sure that deferred probing is delayed until -* late_initcall time. +* all the registered initcall functions at a particular level are completed. +* This function is invoked at every *_initcall_sync level. */ static int deferred_probe_initcall (void ) { - driver_deferred_probe_enable = true; -driver_deferred_probe_trigger (); -/* Sort as many dependencies as possible before exiting initcalls */ -flush_work (&deferred_probe_work); +enable_trigger_defer_cycle (); + driver_deferred_probe_enable = false; +return 0 ; +} +subsys_initcall_sync (deferred_probe_initcall); +fs_initcall_sync (deferred_probe_initcall); +device_initcall_sync (deferred_probe_initcall); + +static int deferred_probe_enable_fn (void ) +{ +/* Enable deferred probing for all time */ +enable_trigger_defer_cycle (); initcalls_done = true;return 0 ; } -late_initcall (deferred_probe_initcall); +late_initcall (deferred_probe_enable_fn);/** * device_is_bound() - Check if device is bound to a driver
Signature · 2 lines
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
Rafael J. Wysocki
maintainerQuoted 13 lines · Rishabh Bhatnagar
Drivers that are registered at an initcall level may have to wait until
late_initbefore the probe deferral mechanism can retry their probe functions. It is possible that their dependencies were resolved much earlier, in some cases even before the next initcall level. Invoke one probe retry cycle at every_syncinitcall level after subsys initcall, allowing these drivers to be probed earlier.Signed-off-by Vikram Mulukutla <[email protected]>Signed-off-by Rishabh Bhatnagar <[email protected]>---
Quoted 7 lines
To give an example many Qualcomm drivers are dependent on the regulator and bus driver. Both the regulator and bus driver are probed in the
subsys_initcalllevel. Now the probe of bus driver requires regulator to be working. If the probe of bus driver happens before regulator, then bus driver's probe will be deferred and all other device's probes which depend on bus driver will also be deferred.
The impact of this problem is reduced if we have this patch.
Please move the above to the changelog proper (ie. above the tags) and resend the patch with CCs to [email protected] and LKML.
Thanks,
Rafael