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Message-ID: <20240901110642.154523-2-o-takashi@sakamocchi.jp>
Date: Sun, 1 Sep 2024 20:06:38 +0900
From: Takashi Sakamoto <o-takashi@...amocchi.jp>
To: linux1394-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org,
linux-sound@...r.kernel.org,
apais@...ux.microsoft.com,
edmund.raile@...tonmail.com,
linux-media@...r.kernel.org,
netdev@...r.kernel.org
Subject: [RFT][PATCH 1/5] firewire: core: allocate workqueue to handle isochronous contexts in card
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, 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.
Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
drivers/firewire/core-card.c | 31 ++++++++++++++++++++++++++++---
drivers/firewire/core.h | 4 ++--
drivers/firewire/ohci.c | 2 +-
include/linux/firewire.h | 2 ++
4 files changed, 33 insertions(+), 6 deletions(-)
diff --git a/drivers/firewire/core-card.c b/drivers/firewire/core-card.c
index e80b762888fa..e0b8423fd4d0 100644
--- a/drivers/firewire/core-card.c
+++ b/drivers/firewire/core-card.c
@@ -571,11 +571,28 @@ 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_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_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 +601,12 @@ 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 +728,8 @@ 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 +741,7 @@ 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 +750,8 @@ 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);
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index 57d101c01e36..96ae366889e0 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -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);
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index a3a37955b174..ad3bdc48f0f5 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -3825,7 +3825,7 @@ 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;
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index 1cca14cf5652..10e135d60824 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -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)
--
2.43.0
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