[PATCH V12 3/5] PCI: Factor out pci_bus_wait_crs()

Sinan Kaya
2017-08-23T04:56:23Z

Configuration Request Retry Status (CRS) was previously hidden inside
pci_bus_read_dev_vendor_id(). We want to add support for CRS in other
situations, such as waiting for a device to become ready after a Function
Level Reset.

Move CRS handling into pci_bus_wait_crs() so it can be called from other
places.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
drivers/pci/pci.h | 1 +
drivers/pci/probe.c | 46 ++++++++++++++++++++++++++++------------------
2 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 7fa583a..56d2515 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -239,6 +239,7 @@ static inline bool pci_bus_crs_visibility_pending(u32 l)
{
return (l & 0xffff) == 0x0001;
}
+bool pci_bus_wait_crs(struct pci_bus *bus, int devfn, u32 l, int 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 2849e0e..93b89dd 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1824,30 +1824,23 @@ 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 timeout)
{
int delay = 1;

- if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, l))
- return false;
+ if ((l & 0xffff) != 0x0001)
+ return true; /* not a CRS completion */

- /* some broken boards return 0 or ~0 if a slot is empty: */
- if (*l == 0xffffffff || *l == 0x00000000 ||
- *l == 0x0000ffff || *l == 0xffff0000)
- return false;
+ if (!timeout)
+ return false; /* CRS, but caller doesn't want to wait */

/*
- * 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).
+ * We got the reserved Vendor ID that indicates a completion with
+ * Configuration Request Retry Status (CRS). Retry until we get a
+ * valid Vendor ID or we time out.
*/
- while ((*l & 0xffff) == 0x0001) {
- if (!crs_timeout)
- return false;
-
- if (delay > crs_timeout) {
+ while ((l & 0xffff) == 0x0001) {
+ if (delay > timeout) {
printk(KERN_WARNING "pci %04x:%02x:%02x.%d: not responding\n",
pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
PCI_FUNC(devfn));
@@ -1857,12 +1850,29 @@ 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))
+ if (pci_bus_read_config_dword(bus, devfn, PCI_VENDOR_ID, &l))
return false;
}

return true;
}
+
+bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
+ int 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;
+
+ if (pci_bus_crs_visibility_pending(*l))
+ return pci_bus_wait_crs(bus, devfn, *l, timeout);
+
+ return true;
+}
EXPORT_SYMBOL(pci_bus_read_dev_vendor_id);

/*
--
1.9.1