X-Git-Url: https://git.rohieb.name/openwrt.git/blobdiff_plain/c0734b8ffe25732738199a03407289ffb450bf0c..0570263dcb87e59113374b8910c30a30c65239d0:/target/linux/ar71xx/files/arch/mips/pci/pci-ar71xx.c

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;
 }