[PATCH V10 1/3] PCI: introduce pci_bus_wait_crs() function

Sinan Kaya
2017-08-11T16:56:34Z

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 <okaya@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