On 8/18/2017 5:32 PM, Bjorn Helgaas wrote:
> While waiting for a device to become ready (i.e., to return a non-CRS
> completion to a read of its Vendor ID), if we got a valid response to the
> very last read before timing out, we printed a warning and gave up on the
> device even though it was actually ready.
>
> For a typical 60s timeout, we wait about 65s (it's not exact because of the
> exponential backoff), but we treated devices that became ready between 33s
> and 65s as though they failed.
>
> Move the Device ID read later so we check whether the device is ready
> immediately, before checking for a timeout.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/pci/probe.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index c31310db0404..08ea844ac4ba 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1849,15 +1849,16 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
>
> msleep(delay);
> delay *= 2;
> - if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
> - return false;
> - /* Card hasn't responded in 60 seconds? Must be stuck. */
> +
There is still a problem here. We'll wait some time above and return without checking if
we actually found the card or not.
> if (delay > crs_timeout) {
> printk(KERN_WARNING "pci %04x:%02x:%02x.%d: not responding\n",
> pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
> PCI_FUNC(devfn));
> return false;
> }
> +
> + if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
> + return false;
> }
>
> return true;
>
>
Here is another shot at it. Sorry, I don't have a diff syntax. I made up the function
by copy paste.
while ((*l & 0xffff) == 0x0001) {
if (!crs_timeout)
return false;
/* Card hasn't responded in 60 seconds? Must be stuck. */
if (delay > crs_timeout) {
printk(KERN_WARNING "pci %04x:%02x:%02x.%d: not responding\n",
pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
PCI_FUNC(devfn));
return false;
}
msleep(delay);
delay *= 2;
if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
return false;
}
--
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.
