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Date: Thu, 11 Jan 2024 09:02:41 -0500
From: Brian Masney <bmasney@redhat.com>
To: Lucas Karpinski <lkarpins@redhat.com>
Cc: Andy Gross <agross@kernel.org>, Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, linux-arm-msm@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arm64: dts: qcom: sa8540p-ride: disable pcie2a node
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On Tue, Jan 09, 2024 at 10:20:50AM -0500, Lucas Karpinski wrote:
> pcie2a and pcie3a both cause interrupt storms to occur. However, when
> both are enabled simultaneously, the two combined interrupt storms will
> lead to rcu stalls. Red Hat is the only company still using this board
> and since we still need pcie3a, just disable pcie2a.
> 
> Signed-off-by: Lucas Karpinski <lkarpins@redhat.com>

Reviewed-by: Brian Masney <bmasney@redhat.com>

To elaborate further: Leaving both pcie2a and pcie3a enabled will lead
to rcu stalls and the board fails to boot when both are enabled. We
have the latest firmware that we've been able to get from QC.
Disabling one of the pcie nodes works around the boot issue. There's
nothing interesting on pcie2a on the development board, and pcie3a is
enabled because it has 10GB ethernet that works upstream.

The interrupt storm on pcie3a can still occur on this platform, however
that's a separate issue.

Brian