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Y. Srinivasan" , Nirmal Patel , Marek Vasut , Rob Herring , Wei Liu , linux-samsung-soc@vger.kernel.org, Marc Zyngier , Naveen Naidu , Joyce Ooi , Dexuan Cui , Jianjun Wang , linux-rockchip@lists.infradead.org, "maintainer:BROADCOM IPROC ARM ARCHITECTURE" , Jonathan Derrick , Xiaowei Song , linux-kernel-mentees@lists.linuxfoundation.org, Robert Richter , Sean V Kelley , Ray Jui , Haiyang Zhang , Ryder Lee , linux-mediatek@lists.infradead.org, skhan@linuxfoundation.org, Matthias Brugger , Stephen Hemminger , linux-arm-kernel@lists.infradead.org, Qiuxu Zhuo , Scott Branden , linuxppc-dev@lists.ozlabs.org, Yoshihiro Shimoda , Krzysztof Kozlowski , linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Lukas Wunner , Jingoo Han , Shawn Guo , =?utf-8?q?Pali_Roh=C3=A1r?= Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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. Add a PCI_ERROR_RESPONSE definition for that and use it where appropriate to make these checks consistent and easier to find. Also add helper definitions SET_PCI_ERROR_RESPONSE and RESPONSE_IS_PCI_ERROR to make the code more readable. Suggested-by: Bjorn Helgaas Signed-off-by: Naveen Naidu Reviewed-by: Pali Rohár --- include/linux/pci.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/linux/pci.h b/include/linux/pci.h index cd8aa6fce204..689c8277c584 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -154,6 +154,15 @@ enum pci_interrupt_pin { /* The number of legacy PCI INTx interrupts */ #define PCI_NUM_INTX 4 +/* + * Reading from a device that doesn't respond typically returns ~0. A + * successful read from a device may also return ~0, so you need additional + * information to reliably identify errors. + */ +#define PCI_ERROR_RESPONSE (~0ULL) +#define SET_PCI_ERROR_RESPONSE(val) (*(val) = ((typeof(*(val))) PCI_ERROR_RESPONSE)) +#define RESPONSE_IS_PCI_ERROR(val) ((val) == ((typeof(val)) PCI_ERROR_RESPONSE)) + /* * pci_power_t values must match the bits in the Capabilities PME_Support * and Control/Status PowerState fields in the Power Management capability.