From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH v2] Re-enable LTR/OBFF when device is owned by pciback Date: Fri, 4 May 2012 09:20:46 -0400 Message-ID: <20120504132046.GD26418@phenom.dumpdata.com> References: <403610A45A2B5242BD291EDAE8B37D300FDAD88C@SHSMSX102.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <403610A45A2B5242BD291EDAE8B37D300FDAD88C@SHSMSX102.ccr.corp.intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Hao, Xudong" Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On Fri, May 04, 2012 at 07:49:21AM +0000, Hao, Xudong wrote: > When PCIE device which has LTR/OBFF capabilities is owned by pciback, LTR/OBFF feature may be disabled. This patch re-enable LTR and OBFF, so that guest with device assigned can be benefitted. > > Changes from v1: > - put the variable definition at the start of function > - add error log report > Don't you need to disable this when the device is un-assigned from the guest? > Signed-off-by: Xudong Hao > > diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c > index 097e536..74fbf23 100644 > --- a/drivers/xen/xen-pciback/pci_stub.c > +++ b/drivers/xen/xen-pciback/pci_stub.c > @@ -313,6 +313,10 @@ static int __devinit pcistub_init_device(struct pci_dev *dev) > struct xen_pcibk_dev_data *dev_data; > int err = 0; > > + /* set default value */ > + unsigned long type = PCI_EXP_OBFF_SIGNAL_ALWAYS; > + int snoop_lat_ns = 1024, nosnoop_lat_ns = 1024; Why these values? Is there a way to fetch optimal values? > + > dev_dbg(&dev->dev, "initializing...\n"); > > /* The PCI backend is not intended to be a module (or to work with > @@ -369,6 +373,28 @@ static int __devinit pcistub_init_device(struct pci_dev *dev) > dev_dbg(&dev->dev, "reset device\n"); > xen_pcibk_reset_device(dev); > > + /* Enable LTR and OBFF before do device assignment */ > + /* LTR(Latency tolerance reporting) allows devices to send > + * messages to the root complex indicating their latency tolerance > + * for snooped & unsnooped memory transactions. > + */ > + err = pci_enable_ltr(dev); > + if (err) > + dev_err(&dev->dev, "Counld not enalbe LTR for device!\n"); > + > + err = pci_set_ltr(dev, snoop_lat_ns, nosnoop_lat_ns); > + if (err) > + dev_err(&dev->dev, "Set LTR latency values failed.\n"); > + > + /* OBFF (optimized buffer flush/fill), where supported, can help > + * improve energy efficiency by giving devices information about > + * when interrupts and other activity will have a reduced power > + * impact. > + */ > + err = pci_enable_obff(dev, type); > + if (err) > + dev_err(&dev->dev, "Counld not enalbe OBFF for device!\n"); > + > dev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED; > return 0; > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel