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[209.17.68.221]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-720bc2c3902sm4096567b3a.136.2024.11.02.07.19.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 Nov 2024 07:19:16 -0700 (PDT) Date: Sat, 2 Nov 2024 23:19:14 +0900 From: Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= To: Siddharth Vadapalli Cc: bhelgaas@google.com, lpieralisi@kernel.org, robh@kernel.org, vigneshr@ti.com, manivannan.sadhasivam@linaro.org, thomas.richard@bootlin.com, linux-omap@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, srk@ti.com Subject: Re: [PATCH] PCI: j721e: Deassert PERST# after a delay of PCIE_T_PVPERL_MS ms Message-ID: <20241102141914.GA3440781@rocinante> References: <20241022083147.2773123-1-s-vadapalli@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241022083147.2773123-1-s-vadapalli@ti.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241102_071918_342510_89654EF2 X-CRM114-Status: GOOD ( 14.12 ) 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 Hello, > According to Section 2.2 of the PCI Express Card Electromechanical > Specification (Revision 5.1), in order to ensure that the power and the > reference clock are stable, PERST# has to be deasserted after a delay of > 100 milliseconds (TPVPERL). Currently, it is being assumed that the power > is already stable, which is not necessarily true. Hence, change the delay > to PCIE_T_PVPERL_MS to guarantee that power and reference clock are stable. [...] > This patch is based on commit > c2ee9f594da8 KVM: selftests: Fix build on on non-x86 architectures > of Mainline Linux. Why KVM? Do you have the link to this commit handy? [...] > if (pcie->reset_gpio) { > - fsleep(PCIE_T_PERST_CLK_US); > + msleep(PCIE_T_PVPERL_MS); fsleep() with the same macro and for the same reason is also used in the j721e_pcie_probe() callback. I think, we would want both changed. Krzysztof