From:   Naveen Naidu <naveennaidu479@gmail.com>
To:     bhelgaas@google.com
Cc:     Naveen Naidu <naveennaidu479@gmail.com>,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        skhan@linuxfoundation.org,
        =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= <kw@linux.com>
Subject: [PATCH v4 21/25] PCI: cpqphp: Use PCI_POSSIBLE_ERROR() to check read from hardware
Date:   Thu, 18 Nov 2021 19:33:31 +0530
Message-Id: <b12005c0d57bb9d4c8b486724d078b7bd92f8321.1637243717.git.naveennaidu479@gmail.com>
In-Reply-To: <cover.1637243717.git.naveennaidu479@gmail.com>
References: <cover.1637243717.git.naveennaidu479@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

An MMIO read from a PCI device that doesn't exist or doesn't respond
causes a PCI error.  There's no real data to return to satisfy the
CPU read, so most hardware fabricates ~0 data.

Use PCI_POSSIBLE_ERROR() to check the response we get when we read
data from hardware.

This helps unify PCI error response checking and make error checks
consistent and easier to find.

Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
---
 drivers/pci/hotplug/cpqphp_ctrl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/hotplug/cpqphp_ctrl.c b/drivers/pci/hotplug/cpqphp_ctrl.c
index ed7b58eb64d2..93fd2a621822 100644
--- a/drivers/pci/hotplug/cpqphp_ctrl.c
+++ b/drivers/pci/hotplug/cpqphp_ctrl.c
@@ -2273,7 +2273,7 @@ static u32 configure_new_device(struct controller  *ctrl, struct pci_func  *func
 		while ((function < max_functions) && (!stop_it)) {
 			pci_bus_read_config_dword(ctrl->pci_bus, PCI_DEVFN(func->device, function), 0x00, &ID);
 
-			if (ID == 0xFFFFFFFF) {
+			if (PCI_POSSIBLE_ERROR(ID)) {
 				function++;
 			} else {
 				/* Setup slot structure. */
@@ -2517,7 +2517,7 @@ static int configure_new_function(struct controller *ctrl, struct pci_func *func
 			pci_bus_read_config_dword(pci_bus, PCI_DEVFN(device, 0), 0x00, &ID);
 			pci_bus->number = func->bus;
 
-			if (ID != 0xFFFFFFFF) {	  /*  device present */
+			if (!PCI_POSSIBLE_ERROR(ID)) {	  /*  device present */
 				/* Setup slot structure. */
 				new_slot = cpqhp_slot_create(hold_bus_node->base);
 
-- 
2.25.1