Kernel is hiding Configuration Request Retry Status (CRS) inside
pci_bus_read_dev_vendor_id() function. We are looking to add support for
Function Level Reset (FLR) where vendor id read returns ~0.

Move CRS handling into its own function so that it can be called from other
places as well.

Signed-off-by: Sinan Kaya <ok...@codeaurora.org>
---
 drivers/pci/pci.h   |  2 ++
 drivers/pci/probe.c | 44 ++++++++++++++++++++++++++++++--------------
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 22e0617..1bbe851 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -235,6 +235,8 @@ enum pci_bar_type {
        pci_bar_mem64,          /* A 64-bit memory BAR */
 };
 
+bool pci_bus_wait_crs(struct pci_bus *bus, int devfn, u32 *l,
+                     int crs_timeout);
 bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *pl,
                                int crs_timeout);
 int pci_setup_device(struct pci_dev *dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index c31310d..b1cb7bd 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1824,29 +1824,17 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
 }
 EXPORT_SYMBOL(pci_alloc_dev);
 
-bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
-                               int crs_timeout)
+bool pci_bus_wait_crs(struct pci_bus *bus, int devfn, u32 *l, int crs_timeout)
 {
        int delay = 1;
 
-       if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
-               return false;
-
-       /* some broken boards return 0 or ~0 if a slot is empty: */
-       if (*l == 0xffffffff || *l == 0x00000000 ||
-           *l == 0x0000ffff || *l == 0xffff0000)
-               return false;
-
        /*
         * Configuration Request Retry Status.  Some root ports return the
         * actual device ID instead of the synthetic ID (0xFFFF) required
         * by the PCIe spec.  Ignore the device ID and only check for
         * (vendor id == 1).
         */
-       while ((*l & 0xffff) == 0x0001) {
-               if (!crs_timeout)
-                       return false;
-
+       do {
                msleep(delay);
                delay *= 2;
                if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
@@ -1858,6 +1846,34 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int 
devfn, u32 *l,
                               PCI_FUNC(devfn));
                        return false;
                }
+       } while ((*l & 0xffff) == 0x0001);
+
+       return true;
+}
+EXPORT_SYMBOL(pci_bus_wait_crs);
+
+bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
+                               int crs_timeout)
+{
+       if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
+               return false;
+
+       /* some broken boards return 0 or ~0 if a slot is empty: */
+       if (*l == 0xffffffff || *l == 0x00000000 ||
+           *l == 0x0000ffff || *l == 0xffff0000)
+               return false;
+
+       /*
+        * Configuration Request Retry Status.  Some root ports return the
+        * actual device ID instead of the synthetic ID (0xFFFF) required
+        * by the PCIe spec.  Ignore the device ID and only check for
+        * (vendor id == 1).
+        */
+       if ((*l & 0xffff) == 0x0001) {
+               if (!crs_timeout)
+                       return false;
+
+               return pci_bus_wait_crs(bus, devfn, l, crs_timeout);
        }
 
        return true;
-- 
1.9.1

Reply via email to