Date: Thu, 8 Apr 2021 10:36:12 -0700 From: John Baldwin <jhb@FreeBSD.org> To: Alexander Motin <mav@FreeBSD.org>, src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: Re: git: 5a898b2b78ce - main - Set PCIe device's Max_Payload_Size to match PCIe root's. Message-ID: <4091ea80-5269-9c78-9fe6-6bba2ed85fbd@FreeBSD.org> In-Reply-To: <202104051440.135EeeTZ095177@gitrepo.freebsd.org> References: <202104051440.135EeeTZ095177@gitrepo.freebsd.org>
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On 4/5/21 7:40 AM, Alexander Motin wrote: > The branch main has been updated by mav: > > URL: https://cgit.FreeBSD.org/src/commit/?id=5a898b2b78ce04d608bbaaa0813424b11f921ae7 > > commit 5a898b2b78ce04d608bbaaa0813424b11f921ae7 > Author: Alexander Motin <mav@FreeBSD.org> > AuthorDate: 2021-04-05 14:34:40 +0000 > Commit: Alexander Motin <mav@FreeBSD.org> > CommitDate: 2021-04-05 14:34:40 +0000 > > Set PCIe device's Max_Payload_Size to match PCIe root's. > > Usually on boot the MPS is already configured by BIOS. But we've > found that on hot-plug it is not true at least for our Supermicro > X11 boards. As result, mismatch between root's configuration of > 256 bytes and device's default of 128 bytes cause problems for some > devices, while others seem to work fine. > > MFC after: 1 month > Sponsored by: iXsystems, Inc. > --- > sys/dev/pci/pci.c | 40 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 40 insertions(+) > > diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c > index ab19d13fc13a..ef138e926b6f 100644 > --- a/sys/dev/pci/pci.c > +++ b/sys/dev/pci/pci.c > @@ -4267,6 +4267,45 @@ pci_create_iov_child_method(device_t bus, device_t pf, uint16_t rid, > } > #endif > > +/* > + * For PCIe device set Max_Payload_Size to match PCIe root's. > + */ > +static void > +pcie_setup_mps(device_t dev) > +{ > + struct pci_devinfo *dinfo = device_get_ivars(dev); > + device_t root; > + uint16_t rmps, mmps, mps; > + > + if (dinfo->cfg.pcie.pcie_location == 0) > + return; > + root = pci_find_pcie_root_port(dev); > + if (root == NULL) > + return; > + /* Check whether the MPS is already configured. */ We tend to add blank lines before comments. > + rmps = pcie_read_config(root, PCIER_DEVICE_CTL, 2) & > + PCIEM_CTL_MAX_PAYLOAD; > + mps = pcie_read_config(dev, PCIER_DEVICE_CTL, 2) & > + PCIEM_CTL_MAX_PAYLOAD; > + if (mps == rmps) > + return; > + /* Check whether the device is capable of the root's MPS. */ > + mmps = (pcie_read_config(dev, PCIER_DEVICE_CAP, 2) & > + PCIEM_CAP_MAX_PAYLOAD) << 5; > + if (rmps > mmps) { > + /* > + * The device is unable to handle root's MPS. Limit root. > + * XXX: We should traverse through all the tree, applying > + * it to all the devices. > + */ Hmmm, limiting the root seems very dubious here. Do you really need this? If not, I'd put it behind a tunable sysctl that defaults to off. Ideally what you'd do here is use an and of the two masks and select one of those bits to choose the value rather than assuming the root can do the device's value. -- John Baldwin
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