On 8/2/2017 4:27 PM, Bjorn Helgaas wrote:
> On Wed, Aug 02, 2017 at 03:15:15PM -0400, Sinan Kaya wrote:
> My hypothesis was that CRS isn't useful on VFs because of sec 2.2.2
> says "FLR ... does not affect its existence in PCI Configuration
> Space". But I think that hypothesis is wrong because sec 3.3.3.1
> does talk about a VF returning CRS.
>
hmm, good catch. I'll drop the first patch.
> The SR-IOV spec (sec 3.4.1.1) says a VF's Vendor ID is read-only
> 0xffff. But I expect CRS visibility (PCIe r3.1, sec 2.3.2) would work
> normally and return a Vendor ID of 0x0001 to indicate CRS for a VF.
>
> Of course, not all Root Ports support CRS software visibility, so
> whatever we do has to work when it's absent.
How about a mixture of old code and new code as follows?
static void pci_flr_wait(struct pci_dev *dev)
{
u32 id;
bool ret = false;
int i = 0;
if (CRS supported) {
/* don't touch the HW before waiting 100ms */
msleep(100);
ret = pci_bus_read_dev_vendor_id(dev->bus, dev->devfn, &id,
60000);
if (ret)
return;
}
do {
msleep(100);
pci_read_config_dword(dev, PCI_COMMAND, &id);
} while (i++ < 10 && id == ~0);
if (id == ~0)
dev_warn(&dev->dev, "Failed to return from FLR\n");
else if (i > 1)
dev_info(&dev->dev, "Required additional %dms to return from
FLR\n",
(i - 1) * 100);
}
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
Foundation Collaborative Project.
