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Thu, 21 Oct 2021 08:11:55 -0700 (PDT) Received: from localhost.localdomain ([2406:7400:63:29a4:d874:a949:6890:f95f]) by smtp.gmail.com with ESMTPSA id c9sm5508027pgq.58.2021.10.21.08.11.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Oct 2021 08:11:54 -0700 (PDT) From: Naveen Naidu To: bhelgaas@google.com Cc: Naveen Naidu , linux-kernel-mentees@lists.linuxfoundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, Thomas Petazzoni , =?utf-8?q?Pali_Roh=C3=A1r?= , Lorenzo Pieralisi , Rob Herring , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , linux-arm-kernel@lists.infradead.org (moderated list:PCI DRIVER FOR AARDVARK (Marvell Armada 3700)) Subject: [PATCH v3 11/25] PCI: aardvark: Remove redundant error fabrication when device read fails Date: Thu, 21 Oct 2021 20:37:36 +0530 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211021_081156_162971_A7AF84D4 X-CRM114-Status: GOOD ( 15.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Reviewed-by: Pali Rohár --- drivers/pci/controller/pci-aardvark.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index 596ebcfcc82d..1af772c76d06 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -893,10 +893,8 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, u32 reg; int ret; - if (!advk_pcie_valid_device(pcie, bus, devfn)) { - *val = 0xffffffff; + if (!advk_pcie_valid_device(pcie, bus, devfn)) return PCIBIOS_DEVICE_NOT_FOUND; - } if (pci_is_root_bus(bus)) return pci_bridge_emul_conf_read(&pcie->bridge, where, @@ -920,7 +918,6 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, *val = CFG_RD_CRS_VAL; return PCIBIOS_SUCCESSFUL; } - *val = 0xffffffff; return PCIBIOS_SET_FAILED; } @@ -955,16 +952,13 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, *val = CFG_RD_CRS_VAL; return PCIBIOS_SUCCESSFUL; } - *val = 0xffffffff; return PCIBIOS_SET_FAILED; } /* Check PIO status and get the read result */ ret = advk_pcie_check_pio_status(pcie, allow_crs, val); - if (ret < 0) { - *val = 0xffffffff; + if (ret < 0) return PCIBIOS_SET_FAILED; - } if (size == 1) *val = (*val >> (8 * (where & 3))) & 0xff;