From: Naveen Naidu <naveennaidu479@gmail.com> To: bhelgaas@google.com Cc: "Rob Herring" <robh@kernel.org>, "Binghui Wang" <wangbinghui@hisilicon.com>, "Krzysztof Wilczyński" <kw@linux.com>, linux-pci@vger.kernel.org, "Xiaowei Song" <songxiaowei@hisilicon.com>, linux-kernel@vger.kernel.org, "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>, linux-kernel-mentees@lists.linuxfoundation.org Subject: [PATCH v4 10/25] PCI: kirin: Remove redundant error fabrication when device read fails Date: Thu, 18 Nov 2021 19:33:20 +0530 [thread overview] Message-ID: <f87e22bc09a471d2cf15ad05dfd6432f57739aed.1637243717.git.naveennaidu479@gmail.com> (raw) In-Reply-To: <cover.1637243717.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/dwc/pcie-kirin.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c index 095afbccf9c1..e6dcac79c02a 100644 --- a/drivers/pci/controller/dwc/pcie-kirin.c +++ b/drivers/pci/controller/dwc/pcie-kirin.c @@ -530,10 +530,8 @@ static int kirin_pcie_rd_own_conf(struct pci_bus *bus, unsigned int devfn, { struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata); - if (PCI_SLOT(devfn)) { - *val = ~0; + if (PCI_SLOT(devfn)) return PCIBIOS_DEVICE_NOT_FOUND; - } *val = dw_pcie_read_dbi(pci, where, size); return PCIBIOS_SUCCESSFUL; -- 2.25.1 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
WARNING: multiple messages have this Message-ID (diff)
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, "Xiaowei Song" <songxiaowei@hisilicon.com>, "Binghui Wang" <wangbinghui@hisilicon.com>, "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>, "Rob Herring" <robh@kernel.org>, "Krzysztof Wilczyński" <kw@linux.com> Subject: [PATCH v4 10/25] PCI: kirin: Remove redundant error fabrication when device read fails Date: Thu, 18 Nov 2021 19:33:20 +0530 [thread overview] Message-ID: <f87e22bc09a471d2cf15ad05dfd6432f57739aed.1637243717.git.naveennaidu479@gmail.com> (raw) In-Reply-To: <cover.1637243717.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/dwc/pcie-kirin.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c index 095afbccf9c1..e6dcac79c02a 100644 --- a/drivers/pci/controller/dwc/pcie-kirin.c +++ b/drivers/pci/controller/dwc/pcie-kirin.c @@ -530,10 +530,8 @@ static int kirin_pcie_rd_own_conf(struct pci_bus *bus, unsigned int devfn, { struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata); - if (PCI_SLOT(devfn)) { - *val = ~0; + if (PCI_SLOT(devfn)) return PCIBIOS_DEVICE_NOT_FOUND; - } *val = dw_pcie_read_dbi(pci, where, size); return PCIBIOS_SUCCESSFUL; -- 2.25.1
next prev parent reply other threads:[~2021-11-18 14:06 UTC|newest] Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-18 14:03 [PATCH v4 00/25] Unify PCI error response checking Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 01/25] PCI: Add PCI_ERROR_RESPONSE and it's related definitions Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 02/25] PCI: Set error response in config access defines when ops->read() fails Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 03/25] PCI: Use PCI_SET_ERROR_RESPONSE() when device not found Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 04/25] PCI: Remove redundant error fabrication when device read fails Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 05/25] PCI: thunder: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 06/25] PCI: iproc: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 07/25] PCI: mediatek: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 08/25] PCI: exynos: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 09/25] PCI: histb: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu [this message] 2021-11-18 14:03 ` [PATCH v4 10/25] PCI: kirin: " Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 11/25] PCI: aardvark: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 12/25] PCI: mvebu: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 13/25] PCI: altera: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 14/25] PCI: rcar: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 15/25] PCI: rockchip: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 16/25] PCI/ERR: Use PCI_POSSIBLE_ERROR() to check read from hardware Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 17/25] PCI: vmd: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 18/25] PCI: pciehp: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 19/25] PCI/DPC: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 20/25] PCI/PME: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 21/25] PCI: cpqphp: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 22/25] PCI: Use PCI_ERROR_RESPONSE to specify hardware error Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 23/25] PCI: keystone: " Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 24/25] PCI: hv: Use PCI_ERROR_RESPONSE to specify hardware read error Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` [PATCH v4 25/25] PCI: xgene: Use PCI_ERROR_RESPONSE to specify hardware error Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 14:03 ` Naveen Naidu 2021-11-18 20:44 ` [PATCH v4 00/25] Unify PCI error response checking Bjorn Helgaas 2021-11-18 20:44 ` Bjorn Helgaas 2021-11-18 20:44 ` Bjorn Helgaas 2021-11-18 20:44 ` Bjorn Helgaas 2021-11-18 20:44 ` Bjorn Helgaas
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