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Fri, 15 Oct 2021 07:43:24 -0700 (PDT) Received: from localhost.localdomain ([2406:7400:63:4806:9a51:7f4b:9b5c:337a]) by smtp.gmail.com with ESMTPSA id f18sm5293491pfa.60.2021.10.15.07.43.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Oct 2021 07:43:23 -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, Ryder Lee , Jianjun Wang , Lorenzo Pieralisi , Rob Herring , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , Matthias Brugger , linux-mediatek@lists.infradead.org (open list:PCIE DRIVER FOR MEDIATEK), linux-arm-kernel@lists.infradead.org (moderated list:ARM/Mediatek SoC support) Subject: [PATCH v2 07/24] PCI: mediatek: Remove redundant error fabrication when device read fails Date: Fri, 15 Oct 2021 20:08:48 +0530 Message-Id: <4aa74ccd31c42b108b61f2ad274bae59a1d25114.1634306198.git.naveennaidu479@gmail.com> 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-20211015_074325_195906_622691C0 X-CRM114-Status: GOOD ( 13.55 ) X-BeenThere: linux-mediatek@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-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=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 --- drivers/pci/controller/pcie-mediatek.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c index 2f3f974977a3..a19f8ec5d392 100644 --- a/drivers/pci/controller/pcie-mediatek.c +++ b/drivers/pci/controller/pcie-mediatek.c @@ -365,19 +365,12 @@ static int mtk_pcie_config_read(struct pci_bus *bus, unsigned int devfn, { struct mtk_pcie_port *port; u32 bn = bus->number; - int ret; port = mtk_pcie_find_port(bus, devfn); - if (!port) { - *val = ~0; + if (!port) return PCIBIOS_DEVICE_NOT_FOUND; - } - - ret = mtk_pcie_hw_rd_cfg(port, bn, devfn, where, size, val); - if (ret) - *val = ~0; - return ret; + return mtk_pcie_hw_rd_cfg(port, bn, devfn, where, size, val); } static int mtk_pcie_config_write(struct pci_bus *bus, unsigned int devfn,