Hi Stefan,
I'm sorry to post messages several times for the patchset if you are still busy. But I'm still waiting for any reaction.
I note that Linus have announced merge window for v5.17 kernel. * https://lore.kernel.org/lkml/CAHk-=wgUkBrUVhjixy4wvrUhPbW-DTgtQubJWVOoLW=O0w...
I'm glad if seeing your action for pull request as a response to the window.
Kind Regards
Takashi Sakamoto
On Fri, Jan 07, 2022 at 08:01:18PM +0900, Takashi Sakamoto wrote:
Hi Stefan,
Wishing you a happy new year.
We are in the last week for release of v5.16 kernel, and soon merge window for v5.17 kernel will be opened if thing goes well. I wish any action for the review process to merge these patches into upstream.
Thanks
Takashi Sakamoto
On Tue, Dec 21, 2021 at 07:54:42PM +0900, Takashi Sakamoto wrote:
Hi Stefan,
Thank you for your long effort to maintain Linux FireWire subsystem. I'd like to use the timestamp function for my integration in ALSA firewire stack planned at next version of Linux kernel. I'm glad if getting to your help for upstreaming.
On Thu, Dec 02, 2021 at 08:34:54PM +0900, Takashi Sakamoto wrote:
Hi,
In 1394 OHCI specification, each descriptor of IR/IT/AR/AT DMA context has timeStamp field. The value of timeStamp field express the time in which the controller accept packet. The resolution of value is isochronous cycle count (8,000 Hz) with second up to 7.
I have a plan to use the value of timeStamp field for ALSA firewire stack so that userspace ALSA PCM/Rawmidi applications can get converted timestamp (ktime) for PCM frame/MIDI message. The timestamp can ideally express finer granularity than the time to invoke IRQ handler (and co).
Current implementation of Linux FireWire subsystem delivers the value of timeStamp field to unit driver for IR/IT/AT DMA context, but not for AR DMA context. Additionally, the way to refer to Isochronous Cycle Timer Register in MMIO region of 1394 OHCI controller is transaction to local node. It includes overhead of transaction and it's preferable to add less-overhead way available in any type of IRQ context.
This patchset adds two functions exposed in kernel space:
- fw_card_read_cycle_time()
- allow unit driver to access to CYCLE_TIME register in MMIO region without initiate transaction
- fw_request_get_timestamp()
- allow unit driver to get timestamp of request packet inner request handler
I note that Hector Martin found kernel null pointer dereference during process to remove PCI card and has posted a patch:
His patch is included in the series with my comment for relevant commit 20802224298c ("firewire: core: add forgotten dummy driver methods, remove unused ones"). The patch is required since unit driver can refer to dummy driver between removal callback of PCI subsystem and removal callback of FireWire subsystem.
Hector Martin (1): firewire: Add dummy read_csr/write_csr functions
Takashi Sakamoto (2): firewire: add kernel API to access CYCLE_TIME register firewire: add kernel API to access packet structure in request structure for AR context
drivers/firewire/core-card.c | 39 +++++++++++++++++++++++++++++ drivers/firewire/core-cdev.c | 6 +++-- drivers/firewire/core-transaction.c | 18 +++++++++++++ include/linux/firewire.h | 3 +++ 4 files changed, 64 insertions(+), 2 deletions(-)
-- 2.32.0
Sincerely yours
Takashi Sakamoto