[PATCH] [40/99] PCI: Set PCIE maxpayload for card during hotplug insertion

From: Andi Kleen
Date: Wed Jul 27 2011 - 18:03:50 EST


2.6.35-longterm review patch. If anyone has any objections, please let me know.

------------------
From: "Jordan_Hargrave@xxxxxxxx" <Jordan_Hargrave@xxxxxxxx>

commit e522a7126c7c144a1dd14c6f217ac31e71082b1d upstream.

The following patch sets the MaxPayload setting to match the parent
reading when inserting a PCIE card into a hotplug slot. On our system,
the upstream bridge is set to 256, but when inserting a card, the card
setting defaults to 128. As soon as I/O is performed to the card it
starts receiving errors since the payload size is too small.

Reviewed-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
Signed-off-by: Jordan Hargrave <jordan_hargrave@xxxxxxxx>
Signed-off-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
drivers/pci/hotplug/pcihp_slot.c | 45 +++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)

Index: linux-2.6.35.y/drivers/pci/hotplug/pcihp_slot.c
===================================================================
--- linux-2.6.35.y.orig/drivers/pci/hotplug/pcihp_slot.c
+++ linux-2.6.35.y/drivers/pci/hotplug/pcihp_slot.c
@@ -158,6 +158,47 @@ static void program_hpp_type2(struct pci
*/
}

+/* Program PCIE MaxPayload setting on device: ensure parent maxpayload <= device */
+static int pci_set_payload(struct pci_dev *dev)
+{
+ int pos, ppos;
+ u16 pctl, psz;
+ u16 dctl, dsz, dcap, dmax;
+ struct pci_dev *parent;
+
+ parent = dev->bus->self;
+ pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
+ if (!pos)
+ return 0;
+
+ /* Read Device MaxPayload capability and setting */
+ pci_read_config_word(dev, pos + PCI_EXP_DEVCTL, &dctl);
+ pci_read_config_word(dev, pos + PCI_EXP_DEVCAP, &dcap);
+ dsz = (dctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5;
+ dmax = (dcap & PCI_EXP_DEVCAP_PAYLOAD);
+
+ /* Read Parent MaxPayload setting */
+ ppos = pci_find_capability(parent, PCI_CAP_ID_EXP);
+ if (!ppos)
+ return 0;
+ pci_read_config_word(parent, ppos + PCI_EXP_DEVCTL, &pctl);
+ psz = (pctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5;
+
+ /* If parent payload > device max payload -> error
+ * If parent payload > device payload -> set speed
+ * If parent payload <= device payload -> do nothing
+ */
+ if (psz > dmax)
+ return -1;
+ else if (psz > dsz) {
+ dev_info(&dev->dev, "Setting MaxPayload to %d\n", 128 << psz);
+ pci_write_config_word(dev, pos + PCI_EXP_DEVCTL,
+ (dctl & ~PCI_EXP_DEVCTL_PAYLOAD) +
+ (psz << 5));
+ }
+ return 0;
+}
+
void pci_configure_slot(struct pci_dev *dev)
{
struct pci_dev *cdev;
@@ -169,6 +210,10 @@ void pci_configure_slot(struct pci_dev *
(dev->class >> 8) == PCI_CLASS_BRIDGE_PCI)))
return;

+ ret = pci_set_payload(dev);
+ if (ret)
+ dev_warn(&dev->dev, "could not set device max payload\n");
+
memset(&hpp, 0, sizeof(hpp));
ret = pci_get_hp_params(dev, &hpp);
if (ret)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/