Re: [PATCH V7 7/9] PCI/sysfs: Add a 10-Bit Tag sysfs file

Bjorn Helgaas
2021-08-04T23:52:14Z

On Wed, Aug 04, 2021 at 09:47:06PM +0800, Dongdong Liu wrote:
> PCIe spec 5.0 r1.0 section 2.2.6.2 says that if an Endpoint supports
> sending Requests to other Endpoints (as opposed to host memory), the
> Endpoint must not send 10-Bit Tag Requests to another given Endpoint
> unless an implementation-specific mechanism determines that the Endpoint
> supports 10-Bit Tag Completer capability. Add a 10bit_tag sysfs file,
> write 0 to disable 10-Bit Tag Requester when the driver does not bind
> the device if the peer device does not support the 10-Bit Tag Completer.
> This will make P2P traffic safe. the 10bit_tag file content indicate
> current 10-Bit Tag Requester Enable status.
>
> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>

> + The file is also writeable, the value only accept by write 0
> + to disable 10-Bit Tag Requester when the driver does not bind
> + the deivce. The typical use case is for p2pdma when the peer
> + device does not support 10-BIT Tag Completer.

s/10-BIT/10-Bit/