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AJvYcCX6FFLRrPxiqfOmCzWNXiqt5FM7GWh0/ombc3UJuYkrno49WZSKd3UnoyvWVduHAece68Y=@lists.linux.dev X-Gm-Message-State: AOJu0Yx+aaes1I0nUwGdAGtBnYmI0VzDe6xE08zqcEefCkmS9Oe9LUvN MEd+ISQJZEiJM+SNj64KlRQ5psSglWFfUbvqIqGEJM3lIlrSxZM4gbnrcNqMWg== X-Google-Smtp-Source: AGHT+IENmUY9fziUvs63gVSy652sJwbamPCQ2VYyNU8dTskEqduYXYWzphnoXxB4WhyxD1leELQILw== X-Received: by 2002:a17:90a:f518:b0:2e2:a3aa:6509 with SMTP id 98e67ed59e1d1-2e5ddb758c5mr3458449a91.14.1729615115179; Tue, 22 Oct 2024 09:38:35 -0700 (PDT) Received: from thinkpad ([36.255.17.224]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e5ad4ed825sm6422503a91.35.2024.10.22.09.38.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Oct 2024 09:38:34 -0700 (PDT) Date: Tue, 22 Oct 2024 22:08:26 +0530 From: Manivannan Sadhasivam To: Bjorn Helgaas Cc: Richard Zhu , kw@linux.com, bhelgaas@google.com, lpieralisi@kernel.org, frank.li@nxp.com, l.stach@pengutronix.de, robh+dt@kernel.org, conor+dt@kernel.org, shawnguo@kernel.org, krzysztof.kozlowski+dt@linaro.org, festevam@gmail.com, s.hauer@pengutronix.de, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, kernel@pengutronix.de, imx@lists.linux.dev Subject: Re: [PATCH v4 1/9] dt-bindings: imx6q-pcie: Add ref clock for i.MX95 PCIe RC Message-ID: <20241022163826.6w3it42o7kbp6ydp@thinkpad> References: <1728981213-8771-2-git-send-email-hongxing.zhu@nxp.com> <20241018231305.GA768070@bhelgaas> Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241018231305.GA768070@bhelgaas> On Fri, Oct 18, 2024 at 06:13:05PM -0500, Bjorn Helgaas wrote: > On Tue, Oct 15, 2024 at 04:33:25PM +0800, Richard Zhu wrote: > > Previous reference clock of i.MX95 PCIe RC is on when system boot to > > kernel. But boot firmware change the behavor, it is off when boot. So it > > needs be turn on when it is used. Also it needs be turn off/on when suspend > > and resume. > > I think this background would make more sense in patch 2. IIUC, > that's where the driver behavior changes to do something with the > "ref" clock. > > I'm not sure how to interpret "Previous reference clock of i.MX95 PCIe > RC is on when system boot to kernel. But boot firmware change the > behavor, it is off when boot." > > Does that mean a previous version of the boot firmware left the ref > clock on at handoff to the OS, and newer firmware turns it off? If > so, I think it would be useful to include information about the > relevant firmware versions. > Most likely that the bootloader *used to* turn on the reference clock and now it decides not to do so (for whatever reason). But ideally, the clock should be voted/enabled by the kernel irrespective of that. So the reference of 'boot firmware' is not relevant here. - Mani -- மணிவண்ணன் சதாசிவம்