Re: [PATCH v2] firewire: ohci: suppress unexpected system reboot in AMD Ryzen machines and ASM108x/VT630x PCIe cards

[Takashi Sakamoto]

Hi,

On Tue, Jan 02, 2024 at 08:01:50PM +0900, Takashi Sakamoto wrote:
> VIA VT6306/6307/6308 provides PCI interface compliant to 1394 OHCI. When
> the hardware is combined with Asmedia ASM1083/1085 PCIe-to-PCI bus bridge,
> it appears that accesses to its 'Isochronous Cycle Timer' register (offset
> 0xf0 on PCI I/O space) often causes unexpected system reboot in any type
> of AMD Ryzen machine (both 0x17 and 0x19 families). It does not appears in
> the other type of machine (AMD pre-Ryzen machine, Intel machine, at least),
> or in the other OHCI 1394 hardware (e.g. Texas Instruments).
> 
> The issue explicitly appears at a commit dcadfd7f7c74 ("firewire: core:
> use union for callback of transaction completion") added to v6.5 kernel.
> It changed 1394 OHCI driver to access to the register every time to
> dispatch local asynchronous transaction. However, the issue exists in
> older version of kernel as long as it runs in AMD Ryzen machine, since
> the access to the register is required to maintain bus time. It is not
> hard to imagine that users experience the unexpected system reboot when
> generating bus reset by plugging any devices in, or reading the register
> by time-aware application programs; e.g. audio sample processing.
> 
> This commit suppresses the unexpected system reboot in the combination of
> hardware. It avoids the access itself. As a result, the software stack can
> not provide the hardware time anymore to unit drivers, userspace
> applications, and nodes in the same IEEE 1394 bus. It brings apparent
> disadvantage since time-aware application programs require it, while
> time-unaware applications are available again; e.g. sbp2.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Jiri Slaby <jirislaby@xxxxxxxxxx>
> Closes: https://bugzilla.suse.com/show_bug.cgi?id=1215436
> Reported-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217994
> Reported-by: Tobias Gruetzmacher <tobias-lists@xxxxx>
> Closes: https://sourceforge.net/p/linux1394/mailman/message/58711901/
> Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2240973
> Closes: https://bugs.launchpad.net/linux/+bug/2043905
> Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
> ---
>  drivers/firewire/ohci.c | 51 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)

Applied to for-linus branch[1]. I'll send it tomorrow and expect it applied
to the mainline kernel, the latest stable kernel, and the longterm kernels.


[1] https://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394.git/log/?h=for-linus

Regards

Takashi Sakamoto