Received-SPF: pass (google.com: domain of linux-kernel+bounces-23760-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Thu, 11 Jan 2024 09:06:15 -0600
From: Andrew Halaney <ahalaney@redhat.com>
To: Brian Masney <bmasney@redhat.com>
Cc: Lucas Karpinski <lkarpins@redhat.com>, 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
Message-ID: <ea4ucaogzewpxqiwg3fegipnhj3mpfxcvm455a3ow6vs4maqeb@usgbirpaeqmj>
References: <qcoqksikfvdqxk6stezbzc7l2br37ccgqswztzqejmhrkhbrwt@ta4npsm35mqk>
 <ZZ_1ARhDxYNk7Gt2@x1>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <ZZ_1ARhDxYNk7Gt2@x1>

On Thu, Jan 11, 2024 at 09:02:41AM -0500, Brian Masney wrote:
> 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.

Related work-around to that in case anyone is interested in the paper
trail:

    https://lore.kernel.org/all/89c13962f5502a89d48f1efb7a6203d155a7e18d.camel@redhat.com/