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[V12,3/6] PCI: loongson: Don't access unexisting devices

Message ID 20220226104731.76776-4-chenhuacai@loongson.cn
State New
Headers show
Series PCI: Loongson pci improvements and quirks | expand

Commit Message

Huacai Chen Feb. 26, 2022, 10:47 a.m. UTC 
On LS2K/LS7A, some unexisting devices don't return 0xffffffff when
scanning. This is a hardware flaw but we can only avoid it by software
now.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 drivers/pci/controller/pci-loongson.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
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Patch

diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c
index 164c0f6e419f..48d9d283cb59 100644
--- a/drivers/pci/controller/pci-loongson.c
+++ b/drivers/pci/controller/pci-loongson.c
@@ -138,6 +138,8 @@  static void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devf
 			       int where)
 {
 	unsigned char busnum = bus->number;
+	unsigned int device = PCI_SLOT(devfn);
+	unsigned int function = PCI_FUNC(devfn);
 	struct loongson_pci *priv = pci_bus_to_loongson_pci(bus);
 
 	if (pci_is_root_bus(bus))
@@ -147,9 +149,12 @@  static void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devf
 	 * Do not read more than one device on the bus other than
 	 * the host bus. For our hardware the root bus is always bus 0.
 	 */
-	if (priv->data->flags & FLAG_DEV_FIX &&
-			busnum != 0 && PCI_SLOT(devfn) > 0)
-		return NULL;
+	if ((priv->data->flags & FLAG_DEV_FIX) && bus->self) {
+		if ((busnum != 0) && (device > 0))
+			return NULL;
+		if ((busnum == 0) && (device >= 9 && device <= 20 && function > 0))
+			return NULL;
+	}
 
 	/* CFG0 can only access standard space */
 	if (where < PCI_CFG_SPACE_SIZE && priv->cfg0_base)