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Date: Wed, 6 Mar 2024 08:20:16 +0100
From: Johan Hovold <johan@kernel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Johan Hovold <johan+linaro@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, linux-arm-msm@vger.kernel.org,
	linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 00/10] arm64: dts: qcom: sc8280xp: PCIe fixes and
 GICv3 ITS enable
Message-ID: <ZegZMNWxCnLbHDxP@hovoldconsulting.com>
References: <20240305081105.11912-1-johan+linaro@kernel.org>
 <20240306063302.GA4129@thinkpad>
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In-Reply-To: <20240306063302.GA4129@thinkpad>

On Wed, Mar 06, 2024 at 12:03:02PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Mar 05, 2024 at 09:10:55AM +0100, Johan Hovold wrote:
> > This series addresses a few problems with the sc8280xp PCIe
> > implementation.
> > 
> > The DWC PCIe controller can either use its internal MSI controller or an
> > external one such as the GICv3 ITS. Enabling the latter allows for
> > assigning affinity to individual interrupts, but results in a large
> > amount of Correctable Errors being logged on both the Lenovo ThinkPad
> > X13s and the sc8280xp-crd reference design.
> > 
> > It turns out that these errors are always generated, but for some yet to
> > be determined reason, the AER interrupts are never received when using
> > the internal MSI controller, which makes the link errors harder to
> > notice.

> > Enabling AER error reporting on sc8280xp could similarly also reveal
> > existing problems with the related sa8295p and sa8540p platforms as they
> > share the base dtsi.
> > 
> > After discussing this with Bjorn Andersson at Qualcomm we have decided
> > to go ahead and disable L0s for all controllers on the CRD and the
> > X13s.
 
> Just received confirmation from Qcom that L0s is not supported for any of the
> PCIe instances in sc8280xp (and its derivatives). Please move the property to
> SoC dtsi.

Ok, thanks for confirming. But then the devicetree property is not the
right way to handle this, and we should disable L0s based on the
compatible string instead.

> > As we are now at 6.8-rc7, I've rebased this series on the Qualcomm PCIe
> > binding rework in linux-next so that the whole series can be merged for
> > 6.9 (the 'aspm-no-l0s' support and devicetree fixes are all marked for
> > stable backport anyway).

I'll respin the series. Looks like we've already missed the chance to
enable ITS in 6.9 anyway.

Johan