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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,
        Russell Currey <ruscur@russell.cc>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        linuxppc-dev@lists.ozlabs.org (open list:PCI ENHANCED ERROR HANDLING
        (EEH) FOR POWERPC)
Subject: [PATCH 17/22] PCI/DPC: Use RESPONSE_IS_PCI_ERROR() to check read from hardware
Date:   Mon, 11 Oct 2021 23:38:27 +0530
Message-Id: <8de64c63fa1559929c83a94a0da8e8f42f0b5377.1633972263.git.naveennaidu479@gmail.com>
In-Reply-To: <cover.1633972263.git.naveennaidu479@gmail.com>
References: <cover.1633972263.git.naveennaidu479@gmail.com>
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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 RESPONSE_IS_PCI_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.

Compile tested only.

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

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index c556e7beafe3..561c44d9429c 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -79,7 +79,7 @@ static bool dpc_completed(struct pci_dev *pdev)
 	u16 status;
 
 	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_STATUS, &status);
-	if ((status != 0xffff) && (status & PCI_EXP_DPC_STATUS_TRIGGER))
+	if ((!RESPONSE_IS_PCI_ERROR(&status)) && (status & PCI_EXP_DPC_STATUS_TRIGGER))
 		return false;
 
 	if (test_bit(PCI_DPC_RECOVERING, &pdev->priv_flags))
@@ -312,7 +312,7 @@ static irqreturn_t dpc_irq(int irq, void *context)
 
 	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
 
-	if (!(status & PCI_EXP_DPC_STATUS_INTERRUPT) || status == (u16)(~0))
+	if (!(status & PCI_EXP_DPC_STATUS_INTERRUPT) || RESPONSE_IS_PCI_ERROR(&status))
 		return IRQ_NONE;
 
 	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
-- 
2.25.1