PCI: pciehp: Use PCI_POSSIBLE_ERROR() to check config reads

When config pci_ops.read() can detect failed PCI transactions, the data
returned to the CPU is PCI_ERROR_RESPONSE (~0 or 0xffffffff).

Obviously a successful PCI config read may *also* return that data if a
config register happens to contain ~0, so it doesn't definitively indicate
an error unless we know the register cannot contain ~0.

Use PCI_POSSIBLE_ERROR() to check the response we get when we read data
from hardware.  This unifies PCI error response checking and makes error
checks consistent and easier to find.

Compile tested only.

Link: https://lore.kernel.org/r/e185b052fbfd530df703a36dd31126cb870eed95.1637243717.git.naveennaidu479@gmail.comSigned-off-by: Naveen Naidu <naveennaidu479@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Lukas Wunner <lukas@wunner.de>

drivers/pci/hotplug/pciehp_hpc.c

@@ -89,7 +89,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
 
 	do {
 		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
-		if (slot_status == (u16) ~0) {
+		if (PCI_POSSIBLE_ERROR(slot_status)) {
 			ctrl_info(ctrl, "%s: no response from device\n",
 				  __func__);
 			return 0;
@@ -165,7 +165,7 @@ static void pcie_do_write_cmd(struct controller *ctrl, u16 cmd,
 	pcie_wait_cmd(ctrl);
 
 	pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
-	if (slot_ctrl == (u16) ~0) {
+	if (PCI_POSSIBLE_ERROR(slot_ctrl)) {
 		ctrl_info(ctrl, "%s: no response from device\n", __func__);
 		goto out;
 	}
@@ -236,7 +236,7 @@ int pciehp_check_link_active(struct controller *ctrl)
 	int ret;
 
 	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
-	if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0)
+	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
 		return -ENODEV;
 
 	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
@@ -443,7 +443,7 @@ int pciehp_card_present(struct controller *ctrl)
 	int ret;
 
 	ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
-	if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0)
+	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(slot_status))
 		return -ENODEV;
 
 	return !!(slot_status & PCI_EXP_SLTSTA_PDS);
@@ -621,7 +621,7 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id)
 
 read_status:
 	pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &status);
-	if (status == (u16) ~0) {
+	if (PCI_POSSIBLE_ERROR(status)) {
 		ctrl_info(ctrl, "%s: no response from device\n", __func__);
 		if (parent)
 			pm_runtime_put(parent);