From: Bjorn Helgaas <helgaas@kernel.org>
To: Vidya Sagar <vidyas@nvidia.com>
Cc: Manikanta Maddireddy <mmaddireddy@nvidia.com>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"lpieralisi@kernel.org" <lpieralisi@kernel.org>,
"kwilczynski@kernel.org" <kwilczynski@kernel.org>,
"mani@kernel.org" <mani@kernel.org>,
"robh@kernel.org" <robh@kernel.org>,
"krzk+dt@kernel.org" <krzk+dt@kernel.org>,
"conor+dt@kernel.org" <conor+dt@kernel.org>,
"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
Jon Hunter <jonathanh@nvidia.com>,
"kishon@kernel.org" <kishon@kernel.org>,
"arnd@arndb.de" <arnd@arndb.de>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"Frank.Li@nxp.com" <Frank.Li@nxp.com>,
"den@valinux.co.jp" <den@valinux.co.jp>,
"hongxing.zhu@nxp.com" <hongxing.zhu@nxp.com>,
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"cassel@kernel.org" <cassel@kernel.org>,
"18255117159@163.com" <18255117159@163.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
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Subject: Re: [PATCH v6 1/9] PCI: tegra194: Drive CLKREQ signal low explicitly
Date: Mon, 2 Mar 2026 17:34:01 -0600 [thread overview]
Message-ID: <20260302233401.GA4036986@bhelgaas> (raw)
In-Reply-To: <2b1f2d0f-b07d-4b14-ac19-78112ca84f05@nvidia.com>
On Fri, Feb 27, 2026 at 12:35:31PM +0000, Vidya Sagar wrote:
> On 24/02/26 00:15, Manikanta Maddireddy wrote:
> > From: Vidya Sagar <vidyas@nvidia.com>
> >
> > Currently, the default setting is that CLKREQ signal of a Root Port
> > is internally overridden to '0' to enable REFCLK to flow out to the slot.
> > It is observed that one of the PCIe switches (case in point Broadcom PCIe
> > Gen4 switch) is propagating the CLKREQ signal of the root port to the
> > downstream side of the switch and expecting the endpoints to pull it low
> > so that it (PCIe switch) can give out the REFCLK although the Switch as
> > such doesn't support CLK-PM or ASPM-L1SS. So, as a workaround, this patch
> > drives the CLKREQ of the Root Port itself low to avoid link up issues
> > between PCIe switch downstream port and endpoints. This is not a wrong
> > thing to do after all the CLKREQ is anyway being overridden to '0'
> > internally and now it is just that the same is being propagated outside
> > also.
Inconsistent styling of "Root Port", "root port". Spec uses
"CLKREQ#".
> > Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
> > Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
> Reviewed-by: Vidya Sagar <vidyas@nvidia.com>
A Reviewed-by tag here seems a little weird since you're the source of
the patch. I'm not sure what that would mean.
next prev parent reply other threads:[~2026-03-02 23:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-23 18:45 [PATCH v6 0/9] Enhancements to pcie-tegra194 driver Manikanta Maddireddy
2026-02-23 18:45 ` [PATCH v6 1/9] PCI: tegra194: Drive CLKREQ signal low explicitly Manikanta Maddireddy
2026-02-27 12:35 ` Vidya Sagar
2026-03-02 23:34 ` Bjorn Helgaas [this message]
2026-03-03 6:51 ` Manikanta Maddireddy
2026-02-23 18:45 ` [PATCH v6 2/9] PCI: tegra194: Calibrate P2U for endpoint mode Manikanta Maddireddy
2026-02-27 12:35 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 3/9] PCI: tegra194: Remove IRQF_ONESHOT flag during Endpoint interrupt registration Manikanta Maddireddy
2026-02-27 12:35 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 4/9] PCI: tegra194: Enable DMA interrupt Manikanta Maddireddy
2026-02-27 12:36 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 5/9] PCI: tegra194: Enable hardware hot reset mode in Endpoint Manikanta Maddireddy
2026-02-27 12:36 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 6/9] PCI: tegra194: Disable L1.2 capability of Tegra234 EP Manikanta Maddireddy
2026-02-27 12:36 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 7/9] dt-bindings: PCI: tegra194: Add monitor clock support Manikanta Maddireddy
2026-02-27 12:36 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 8/9] PCI: tegra194: Add core " Manikanta Maddireddy
2026-02-27 12:36 ` Vidya Sagar
2026-02-23 18:45 ` [PATCH v6 9/9] PCI: tegra194: Add ASPM L1 entrance latency config Manikanta Maddireddy
2026-02-27 12:36 ` Vidya Sagar
2026-02-27 16:59 ` [PATCH v6 0/9] Enhancements to pcie-tegra194 driver Jon Hunter
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