The batch of changes includes the followwing:
- Replacing tasklet with usual workqueue for isochronous context
- Replacing IDR with XArray
- Utilizing guard macro where possible
- Printing deprecation warning when enabling debug parameter of
firewire-ohci module
Additionally, it includes a single patch for sound subsystem which the
subsystem maintainer acked:
- Switching to nonatomic PCM operation
In FireWire subsystem, tasklet has been used as the bottom half of 1394
OHCi hardIRQ so long. In the recent kernel updates, BH workqueue has
been available, and some developers have proposed replacing tasklet with
BH workqueue. While it is fortunate that developers are still considering
the legacy subsystem, a simple replacement is not necessarily suitable.
As a first step towards dropping tasklet, I've investigated the
feasibility for 1394 OHCI isochronous context, and concluded that usual
workqueue is available. In the context, the batch of packets is processed
in the specific queue, thus the timing jitter caused by task scheduling is
not so critical. Additionally, DMA transmission can be scheduled
per-packet basis, therefore the context can be sleep between the operation
of transmissions. Furthermore, in-kernel protocol implementation involves
some CPU-bound tasks, which can sometimes consumes CPU time so long. These
characteristics suggest that usual workqueue is suitable, through BH
workqueues are not.
The replacement with usual workqueue allows unit drivers to process the
content of packets in non-atomic context. It brings some reliefs to some
drivers in sound subsystem that spin-lock is not mandatory anymore during
isochronous packet processing.
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Merge tag 'firewire-updates-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394
Pull firewire updates from Takashi Sakamoto:
"In the FireWire subsystem, tasklets have been used as the bottom half
of 1394 OHCi hardIRQ. In recent kernel updates, BH workqueues have
become available, and some developers have proposed replacing the
tasklet with a BH workqueue.
As a first step towards dropping tasklet use, the 1394 OHCI
isochronous context can use regular workqueues. In this context, the
batch of packets is processed in the specific queue, thus the timing
jitter caused by task scheduling is not so critical.
Additionally, DMA transmission can be scheduled per-packet basis,
therefore the context can be sleep between the operation of
transmissions. Furthermore, in-kernel protocol implementation involves
some CPU-bound tasks, which can sometimes consumes CPU time so long.
These characteristics suggest that normal workqueues are suitable,
through BH workqueues are not.
The replacement with a workqueue allows unit drivers to process the
content of packets in non-atomic context. It brings some reliefs to
some drivers in sound subsystem that spin-lock is not mandatory
anymore during isochronous packet processing.
Summary:
- Replace tasklet with workqueue for isochronous context
- Replace IDR with XArray
- Utilize guard macro where possible
- Print deprecation warning when enabling debug parameter of
firewire-ohci module
- Switch to nonatomic PCM operation"
* tag 'firewire-updates-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394: (55 commits)
firewire: core: rename cause flag of tracepoints event
firewire: core: update documentation of kernel APIs for flushing completions
firewire: core: add helper function to retire descriptors
Revert "firewire: core: move workqueue handler from 1394 OHCI driver to core function"
Revert "firewire: core: use mutex to coordinate concurrent calls to flush completions"
firewire: core: use mutex to coordinate concurrent calls to flush completions
firewire: core: move workqueue handler from 1394 OHCI driver to core function
firewire: core: fulfill documentation of fw_iso_context_flush_completions()
firewire: core: expose kernel API to schedule work item to process isochronous context
firewire: core: use WARN_ON_ONCE() to avoid superfluous dumps
ALSA: firewire: use nonatomic PCM operation
firewire: core: non-atomic memory allocation for isochronous event to user client
firewire: ohci: operate IT/IR events in sleepable work process instead of tasklet softIRQ
firewire: core: add local API to queue work item to workqueue specific to isochronous contexts
firewire: core: allocate workqueue to handle isochronous contexts in card
firewire: ohci: obsolete direct usage of printk_ratelimit()
firewire: ohci: deprecate debug parameter
firewire: core: update fw_device outside of device_find_child()
firewire: ohci: fix error path to detect initiated reset in TI TSB41BA3D phy
firewire: core/ohci: minor refactoring for computation of configuration ROM size
...
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