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firewire: core: allocate workqueue to handle isochronous contexts in card

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This commit adds a workqueue dedicated for isochronous context processing.

The workqueue is allocated per instance of fw_card structure to satisfy the
following characteristics descending from 1394 OHCI specification:

In 1394 OHCI specification, memory pages are reserved to each isochronous
context dedicated to DMA transmission. It allows to operate these
per-context pages concurrently. Software can schedule hardware interrupt
for several isochronous context to the same cycle, thus WQ_UNBOUND is
specified. Additionally, it is sleepable to operate the content of pages,
thus WQ_BH is not used.

The isochronous context delivers the packets with time stamp, thus
WQ_HIGHPRI is specified for semi real-time data such as IEC 61883-1/6
protocol implemented by ALSA firewire stack. The isochronous context is not
used by the implementation of SCSI over IEEE1394 protocol (sbp2), thus
WQ_MEM_RECLAIM is not specified.

It is useful for users to adjust cpu affinity of the workqueue depending
on their work loads, thus WQ_SYS is specified to expose the attributes to
user space.

Tested-by: Edmund Raile <edmund.raile@protonmail.com>
Link: https://lore.kernel.org/r/20240904125155.461886-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
This commit is contained in:
Takashi Sakamoto 2024-09-04 21:51:50 +09:00
parent 7d35a00603
commit c6fb88a527
4 changed files with 35 additions and 6 deletions
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33
drivers/firewire/core-card.c
View File

@ -571,11 +571,30 @@ void fw_card_initialize(struct fw_card *card,
}
EXPORT_SYMBOL(fw_card_initialize);
int fw_card_add(struct fw_card *card,
u32 max_receive, u32 link_speed, u64 guid)
int fw_card_add(struct fw_card *card, u32 max_receive, u32 link_speed, u64 guid,
unsigned int supported_isoc_contexts)
{
struct workqueue_struct *isoc_wq;
int ret;
// This workqueue should be:
// * != WQ_BH Sleepable.
// * == WQ_UNBOUND Any core can process data for isoc context. The
// implementation of unit protocol could consumes the core
// longer somehow.
// * != WQ_MEM_RECLAIM Not used for any backend of block device.
// * == WQ_FREEZABLE Isochronous communication is at regular interval in real
// time, thus should be drained if possible at freeze phase.
// * == WQ_HIGHPRI High priority to process semi-realtime timestamped data.
// * == WQ_SYSFS Parameters are available via sysfs.
// * max_active == n_it + n_ir A hardIRQ could notify events for multiple isochronous
// contexts if they are scheduled to the same cycle.
isoc_wq = alloc_workqueue("firewire-isoc-card%u",
WQ_UNBOUND | WQ_FREEZABLE | WQ_HIGHPRI | WQ_SYSFS,
supported_isoc_contexts, card->index);
if (!isoc_wq)
return -ENOMEM;
card->max_receive = max_receive;
card->link_speed = link_speed;
card->guid = guid;
@ -584,9 +603,12 @@ int fw_card_add(struct fw_card *card,
generate_config_rom(card, tmp_config_rom);
ret = card->driver->enable(card, tmp_config_rom, config_rom_length);
if (ret < 0)
if (ret < 0) {
destroy_workqueue(isoc_wq);
return ret;
}
card->isoc_wq = isoc_wq;
list_add_tail(&card->link, &card_list);
return 0;
@ -708,6 +730,8 @@ void fw_core_remove_card(struct fw_card *card)
{
struct fw_card_driver dummy_driver = dummy_driver_template;
might_sleep();
card->driver->update_phy_reg(card, 4,
PHY_LINK_ACTIVE | PHY_CONTENDER, 0);
fw_schedule_bus_reset(card, false, true);
@ -719,6 +743,7 @@ void fw_core_remove_card(struct fw_card *card)
dummy_driver.free_iso_context = card->driver->free_iso_context;
dummy_driver.stop_iso = card->driver->stop_iso;
card->driver = &dummy_driver;
drain_workqueue(card->isoc_wq);
scoped_guard(spinlock_irqsave, &card->lock)
fw_destroy_nodes(card);
@ -727,6 +752,8 @@ void fw_core_remove_card(struct fw_card *card)
fw_card_put(card);
wait_for_completion(&card->done);
destroy_workqueue(card->isoc_wq);
WARN_ON(!list_empty(&card->transaction_list));
}
EXPORT_SYMBOL(fw_core_remove_card);

4
drivers/firewire/core.h
View File

@ -115,8 +115,8 @@ struct fw_card_driver {
void fw_card_initialize(struct fw_card *card,
const struct fw_card_driver *driver, struct device *device);
int fw_card_add(struct fw_card *card,
u32 max_receive, u32 link_speed, u64 guid);
int fw_card_add(struct fw_card *card, u32 max_receive, u32 link_speed, u64 guid,
unsigned int supported_isoc_contexts);
void fw_core_remove_card(struct fw_card *card);
int fw_compute_block_crc(__be32 *block);
void fw_schedule_bm_work(struct fw_card *card, unsigned long delay);

2
drivers/firewire/ohci.c
View File

@ -3827,7 +3827,7 @@ static int pci_probe(struct pci_dev *dev,
goto fail_msi;
}
err = fw_card_add(&ohci->card, max_receive, link_speed, guid);
err = fw_card_add(&ohci->card, max_receive, link_speed, guid, ohci->n_it + ohci->n_ir);
if (err)
goto fail_irq;

2
include/linux/firewire.h
View File

@ -134,6 +134,8 @@ struct fw_card {
__be32 topology_map[(CSR_TOPOLOGY_MAP_END - CSR_TOPOLOGY_MAP) / 4];
__be32 maint_utility_register;
struct workqueue_struct *isoc_wq;
};
static inline struct fw_card *fw_card_get(struct fw_card *card)