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, "Joyce Ooi" <joyce.ooi@intel.com>, "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>, "Rob Herring" <robh@kernel.org>, "Krzysztof Wilczyński" <kw@linux.com> Subject: [PATCH v2 13/24] PCI: altera: Remove redundant error fabrication when device read fails Date: Fri, 15 Oct 2021 20:08:54 +0530 [thread overview] Message-ID: <178022540498862f4d16e5738b5d5c1fac008afe.1634306198.git.naveennaidu479@gmail.com> (raw) In-Reply-To: <cover.1634306198.git.naveennaidu479@gmail.com> 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. The host controller drivers sets the error response values (~0) and returns an error when faulty hardware read occurs. But the error response value (~0) is already being set in PCI_OP_READ and PCI_USER_READ_CONFIG whenever a read by host controller driver fails. Thus, it's no longer necessary for the host controller drivers to fabricate any error response. This helps unify PCI error response checking and make error check consistent and easier to find. Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com> --- drivers/pci/controller/pcie-altera.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/pci/controller/pcie-altera.c b/drivers/pci/controller/pcie-altera.c index 2513e9363236..a6bdf9aff833 100644 --- a/drivers/pci/controller/pcie-altera.c +++ b/drivers/pci/controller/pcie-altera.c @@ -510,10 +510,8 @@ static int altera_pcie_cfg_read(struct pci_bus *bus, unsigned int devfn, if (altera_pcie_hide_rc_bar(bus, devfn, where)) return PCIBIOS_BAD_REGISTER_NUMBER; - if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn))) { - *value = 0xffffffff; + if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn))) return PCIBIOS_DEVICE_NOT_FOUND; - } return _altera_pcie_cfg_read(pcie, bus->number, devfn, where, size, value); -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Naveen Naidu <naveennaidu479@gmail.com> To: bhelgaas@google.com Cc: "Rob Herring" <robh@kernel.org>, "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>, "Krzysztof Wilczyński" <kw@linux.com>, "Joyce Ooi" <joyce.ooi@intel.com>, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: [PATCH v2 13/24] PCI: altera: Remove redundant error fabrication when device read fails Date: Fri, 15 Oct 2021 20:08:54 +0530 [thread overview] Message-ID: <178022540498862f4d16e5738b5d5c1fac008afe.1634306198.git.naveennaidu479@gmail.com> (raw) In-Reply-To: <cover.1634306198.git.naveennaidu479@gmail.com> 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. The host controller drivers sets the error response values (~0) and returns an error when faulty hardware read occurs. But the error response value (~0) is already being set in PCI_OP_READ and PCI_USER_READ_CONFIG whenever a read by host controller driver fails. Thus, it's no longer necessary for the host controller drivers to fabricate any error response. This helps unify PCI error response checking and make error check consistent and easier to find. Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com> --- drivers/pci/controller/pcie-altera.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/pci/controller/pcie-altera.c b/drivers/pci/controller/pcie-altera.c index 2513e9363236..a6bdf9aff833 100644 --- a/drivers/pci/controller/pcie-altera.c +++ b/drivers/pci/controller/pcie-altera.c @@ -510,10 +510,8 @@ static int altera_pcie_cfg_read(struct pci_bus *bus, unsigned int devfn, if (altera_pcie_hide_rc_bar(bus, devfn, where)) return PCIBIOS_BAD_REGISTER_NUMBER; - if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn))) { - *value = 0xffffffff; + if (!altera_pcie_valid_device(pcie, bus, PCI_SLOT(devfn))) return PCIBIOS_DEVICE_NOT_FOUND; - } return _altera_pcie_cfg_read(pcie, bus->number, devfn, where, size, value); -- 2.25.1 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
next prev parent reply other threads:[~2021-10-15 14:45 UTC|newest] Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-15 14:35 [PATCH v2 00/24] Unify PCI error response checking Naveen Naidu 2021-10-15 14:35 ` Naveen Naidu 2021-10-15 14:35 ` Naveen Naidu 2021-10-15 14:35 ` Naveen Naidu 2021-10-15 14:35 ` Naveen Naidu 2021-10-15 14:35 ` Naveen Naidu 2021-10-15 14:28 ` [PATCH v2 01/24] PCI: Add PCI_ERROR_RESPONSE and it's related definitions Naveen Naidu 2021-10-15 14:28 ` Naveen Naidu 2021-10-20 13:24 ` Rob Herring 2021-10-20 13:24 ` Rob Herring 2021-10-15 14:28 ` [PATCH v2 02/24] PCI: Set error response in config access defines when ops->read() fails Naveen Naidu 2021-10-15 14:28 ` Naveen Naidu 2021-10-20 13:41 ` Rob Herring 2021-10-20 13:41 ` Rob Herring 2021-10-20 13:52 ` Pali Rohár 2021-10-20 13:52 ` Pali Rohár 2021-10-20 15:13 ` Naveen Naidu 2021-10-20 15:13 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 03/24] PCI: Unify PCI error response checking Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-20 13:13 ` Rob Herring 2021-10-20 13:13 ` Rob Herring 2021-10-20 15:15 ` Naveen Naidu 2021-10-20 15:15 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 04/24] PCI: Remove redundant error fabrication when device read fails Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-20 13:42 ` Rob Herring 2021-10-20 13:42 ` Rob Herring 2021-10-15 14:38 ` [PATCH v2 05/24] PCI: thunder: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 06/24] PCI: iproc: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 16:49 ` Ray Jui 2021-10-15 16:49 ` Ray Jui 2021-10-15 16:49 ` Ray Jui via Linux-kernel-mentees 2021-10-15 17:05 ` Naveen Naidu 2021-10-15 17:05 ` Naveen Naidu 2021-10-15 17:05 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 07/24] PCI: mediatek: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 08/24] PCI: exynos: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 09/24] PCI: histb: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 10/24] PCI: kirin: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 11/24] PCI: aardvark: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 12/24] PCI: mvebu: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu [this message] 2021-10-15 14:38 ` [PATCH v2 13/24] PCI: altera: " Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 14/24] PCI: rcar: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-18 11:32 ` Geert Uytterhoeven 2021-10-18 11:32 ` Geert Uytterhoeven 2021-10-18 11:51 ` Naveen Naidu 2021-10-18 11:51 ` Naveen Naidu 2021-10-18 12:00 ` Geert Uytterhoeven 2021-10-18 12:00 ` Geert Uytterhoeven 2021-10-15 14:38 ` [PATCH v2 15/24] PCI: rockchip: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 16/24] PCI/ERR: Use RESPONSE_IS_PCI_ERROR() to check read from hardware Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 17/24] PCI: vmd: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 14:52 ` Naveen Naidu 2021-10-15 14:52 ` Naveen Naidu 2021-10-15 14:38 ` [PATCH v2 18/24] PCI: pciehp: " Naveen Naidu 2021-10-15 14:38 ` Naveen Naidu 2021-10-15 15:15 ` Naveen Naidu 2021-10-15 15:15 ` Naveen Naidu 2021-10-15 14:39 ` [PATCH v2 19/24] PCI/DPC: " Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` [PATCH v2 20/24] PCI/PME: " Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` [PATCH v2 21/24] PCI: cpqphp: " Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` [PATCH v2 22/24] PCI: keystone: Use PCI_ERROR_RESPONSE to specify hardware error Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` [PATCH v2 23/24] PCI: hv: Use PCI_ERROR_RESPONSE to specify hardware read error Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` [PATCH v2 24/24] PCI: xgene: Use PCI_ERROR_RESPONSE to specify hardware error Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu 2021-10-15 14:39 ` Naveen Naidu
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