From 66c3f05ddc538ee796321210c906b6ae6fc0792a Mon Sep 17 00:00:00 2001
From: Guenter Roeck <linux@roeck-us.net>
Date: Mon, 5 Apr 2021 21:29:22 -0700
Subject: [PATCH] pcnet32: Use pci_resource_len to validate PCI resource
Git-commit: 66c3f05ddc538ee796321210c906b6ae6fc0792a
Patch-mainline: v5.12-rc7
References: git-fixes

pci_resource_start() is not a good indicator to determine if a PCI
resource exists or not, since the resource may start at address 0.
This is seen when trying to instantiate the driver in qemu for riscv32
or riscv64.

pci 0000:00:01.0: reg 0x10: [io  0x0000-0x001f]
pci 0000:00:01.0: reg 0x14: [mem 0x00000000-0x0000001f]
...
Pcnet32: card has no PCI IO resources, aborting

Use pci_resouce_len() instead.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/ethernet/amd/pcnet32.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/amd/pcnet32.c
+++ b/drivers/net/ethernet/amd/pcnet32.c
@@ -1543,8 +1543,7 @@ pcnet32_probe_pci(struct pci_dev *pdev,
 	}
 	pci_set_master(pdev);
 
-	ioaddr = pci_resource_start(pdev, 0);
-	if (!ioaddr) {
+	if (!pci_resource_len(pdev, 0)) {
 		if (pcnet32_debug & NETIF_MSG_PROBE)
 			pr_err("card has no PCI IO resources, aborting\n");
 		return -ENODEV;
@@ -1556,6 +1555,8 @@ pcnet32_probe_pci(struct pci_dev *pdev,
 			pr_err("architecture does not support 32bit PCI busmaster DMA\n");
 		return err;
 	}
+
+	ioaddr = pci_resource_start(pdev, 0);
 	if (!request_region(ioaddr, PCNET32_TOTAL_SIZE, "pcnet32_probe_pci")) {
 		if (pcnet32_debug & NETIF_MSG_PROBE)
 			pr_err("io address range already allocated\n");