[PATCH u-boot] dm: pci: Fix handling of errors when scanning device

[Marek Behún]

From: Pali Rohár <pali at kernel.org>

Some PCIe controller's read_config() method support indicating error
directly via return value, but some cannot distinguish all-ones (or
all-zeros) read response from an error.

The current code in pci_bind_bus_devices() interprets all-ones /
all-zeros in PCI_VENDOR_ID register as "nothing connected", and
continues the cycle, but an error returned via return value breaks the
cycle.

This is wrong for the PCIe controllers which return this error via
return value.

Handle all errors when reading PCI_VENDOR_ID the same way.

This fixes enumeration of PCI devices for example when there is a PCI
bridge connected behind another PCI bridge and not all ports are
connected to a device, and the controller (for example Aardvark)
translates the UR error (Unsupported Request) as -EOPNOTSUPP.

Signed-off-by: Pali Rohár <pali at kernel.org>
Signed-off-by: Marek Behún <marek.behun at nic.cz>
---
 drivers/pci/pci-uclass.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index ce2eb5da2c..4d0e938fe5 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -856,10 +856,7 @@ int pci_bind_bus_devices(struct udevice *bus)
 		/* Check only the first access, we don't expect problems */
 		ret = pci_bus_read_config(bus, bdf, PCI_VENDOR_ID, &vendor,
 					  PCI_SIZE_16);
-		if (ret)
-			goto error;
-
-		if (vendor == 0xffff || vendor == 0x0000)
+		if (ret || vendor == 0xffff || vendor == 0x0000)
 			continue;
 
 		pci_bus_read_config(bus, bdf, PCI_HEADER_TYPE,
@@ -940,10 +937,6 @@ int pci_bind_bus_devices(struct udevice *bus)
 	}
 
 	return 0;
-error:
-	printf("Cannot read bus configuration: %d\n", ret);
-
-	return ret;
 }
 
 static void decode_regions(struct pci_controller *hose, ofnode parent_node,
-- 
2.32.0