From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Richard Zhu <hongxing.zhu@nxp.com>,
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
Date: Tue, 22 Oct 2024 22:08:26 +0530 [thread overview]
Message-ID: <20241022163826.6w3it42o7kbp6ydp@thinkpad> (raw)
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
next prev parent reply other threads:[~2024-10-22 16:38 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-15 8:33 [PATCH v4 0/9] A bunch of changes to refine i.MX PCIe driver Richard Zhu
2024-10-15 8:33 ` [PATCH v4 1/9] dt-bindings: imx6q-pcie: Add ref clock for i.MX95 PCIe RC Richard Zhu
2024-10-18 23:13 ` Bjorn Helgaas
2024-10-21 15:26 ` Frank Li
2024-10-22 16:38 ` Manivannan Sadhasivam [this message]
2024-10-15 8:33 ` [PATCH v4 2/9] PCI: imx6: Add ref clock for i.MX95 PCIe Richard Zhu
2024-10-22 16:46 ` Manivannan Sadhasivam
2024-10-24 7:42 ` Hongxing Zhu
2024-10-15 8:33 ` [PATCH v4 3/9] PCI: imx6: Fetch dbi2 and iATU base addesses from DT Richard Zhu
2024-10-22 16:48 ` Manivannan Sadhasivam
2024-10-22 19:56 ` Frank Li
2024-10-15 8:33 ` [PATCH v4 4/9] PCI: imx6: Correct controller_id generation logic for i.MX7D Richard Zhu
2024-10-22 16:55 ` Manivannan Sadhasivam
2024-10-24 7:42 ` Hongxing Zhu
2024-10-15 8:33 ` [PATCH v4 5/9] PCI: imx6: Make core reset assertion deassertion symmetric Richard Zhu
2024-10-22 16:59 ` Manivannan Sadhasivam
2024-10-15 8:33 ` [PATCH v4 6/9] PCI: imx6: Make *_enable_ref_clk() function symmetric Richard Zhu
2024-10-22 17:05 ` Manivannan Sadhasivam
2024-10-15 8:33 ` [PATCH v4 7/9] PCI: imx6: Use dwc common suspend resume method Richard Zhu
2024-10-22 17:18 ` Manivannan Sadhasivam
2024-10-22 19:42 ` Frank Li
2024-10-24 7:43 ` Hongxing Zhu
2024-10-15 8:33 ` [PATCH v4 8/9] PCI: imx6: Add i.MX8MQ i.MX8Q and i.MX95 PCIe PM support Richard Zhu
2024-10-15 8:33 ` [PATCH v4 9/9] arm64: dts: imx95: Add ref clock for i.MX95 PCIe Richard Zhu
2024-10-22 17:20 ` Manivannan Sadhasivam
2024-10-18 1:39 ` [PATCH v4 0/9] A bunch of changes to refine i.MX PCIe driver Hongxing Zhu
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