Re: [PATCH 09/13] PCI/P2PDMA: Document ACS egress control handling
Leon Romanovsky <[email protected]> Wed, 5 Aug 2026 12:02:39 +0300
| Newsgroups | org.kernel.vger.linux-pci,org.kernel.vger.linux-doc,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <20260805090239.GB23431@unreal> |
On Tue, Aug 04, 2026 at 04:01:41PM -0600, Logan Gunthorpe wrote: > > > On 2026-08-02 09:09, Leon Romanovsky wrote: > > +ACS P2P Egress Control does not by itself force a transaction upstream. A > > +clear Egress Control Vector bit for the peer port permits direct routing; a > > +set bit redirects the request upstream when P2P Request Redirect is enabled. > > +When Request Redirect is disabled, a set vector bit causes an ACS Violation > > +instead. The kernel evaluates these controls together and routes P2P DMA > > +through the host bridge when the direct path is blocked or cannot be > > +determined. > > One small nit here: I'd put commas around "by itself" to make it read a > little easier: > > "ACS P2P Egress Control does not, by itself, force a transaction..." > > Other than that: > > Reviewed-by: Logan Gunthorpe <[email protected]> Thanks for the review. I understand the effort involved and truly appreciate it.