ar71xx: merge pci register read workaround from r24236

git-svn-id: svn://svn.openwrt.org/openwrt/branches/backfire@24240 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/ar71xx/files/arch/mips/pci/pci-ar71xx.c b/target/linux/ar71xx/files/arch/mips/pci/pci-ar71xx.c
index 7d0eee9dbfb365a5c0bbf0c11a173bb84cf5a10f..a75b9ab6861435be5c2f488dcaf7607cf9d37c93 100644 (file)
--- a/target/linux/ar71xx/files/arch/mips/pci/pci-ar71xx.c
+++ b/target/linux/ar71xx/files/arch/mips/pci/pci-ar71xx.c
@@ -136,6 +136,7 @@ static int ar71xx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
        static u32 mask[8] = {0, 0xff, 0xffff, 0, 0xffffffff, 0, 0, 0};
        unsigned long flags;
        u32 data;
+       int retry = 0;
        int ret;
 
        ret = PCIBIOS_SUCCESSFUL;
@@ -143,6 +144,7 @@ static int ar71xx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
        DBG("PCI: read config: %02x:%02x.%01x/%02x:%01d\n", bus->number,
                        PCI_SLOT(devfn), PCI_FUNC(devfn), where, size);
 
+retry:
        spin_lock_irqsave(&ar71xx_pci_lock, flags);
 
        if (bus->number == 0 && devfn == 0) {
@@ -176,6 +178,14 @@ static int ar71xx_pci_read_config(struct pci_bus *bus, unsigned int devfn,
 
        *value = (data >> (8 * (where & 3))) & mask[size & 7];
 
+       /*
+        * PCI controller bug: sometimes reads to the PCI_COMMAND register
+        * return 0xffff, even though the PCI trace shows the correct value.
+        * Work around this by retrying reads to this register
+        */
+       if (where == PCI_COMMAND && (*value & 0xffff) == 0xffff && retry++ < 2)
+               goto retry;
+
        return ret;
 }