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Subject[PATCH] pci/probe: Ignore the device id while handling CRS
Some root ports may return the actual device id returned by the
endpoint, instead of faking up a synthetic id (0xFFFF) as specified
by the PCIe spec (sec 2.3.2). We have seen such broken devices in the
past that match this behaviour:
(Ref: https://lkml.org/lkml/2007/11/1/198)

To take care of the same, CRS was disabled then, however, we want to
enable CRS now (https://lkml.org/lkml/2014/9/2/509), but still do not
want to break such devices. Thus check only against the
(vendor id == 1) and ignore the device id.

Signed-off-by: Rajat Jain <rajatxjain@gmail.com>
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
---
drivers/pci/probe.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 3c4c35c..0076a9b 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1305,8 +1305,13 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
*l == 0x0000ffff || *l == 0xffff0000)
return false;

- /* Configuration request Retry Status */
- while (*l == 0xffff0001) {
+ /*
+ * Configuration request Retry Status. Note that some root ports
+ * are broken and may return actual device ID instead of a synthetic ID
+ * (0xFFFF) to be faked as per the PCIe spec. Hence ignore the device ID
+ * and only check for (vendor id == 1)
+ */
+ while (*l & 0xffff == 0x0001) {
if (!crs_timeout)
return false;

--
1.7.9.5


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