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-rw-r--r--target/linux/ar71xx/files/arch/mips/pci/pci-ar71xx.c10
1 files changed, 10 insertions, 0 deletions
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 c6c6e5583..5f10d6a65 100644
--- 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;
}