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Date: Fri, 16 Feb 2024 22:24:06 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Johan Hovold <johan@kernel.org>, Johan Hovold <johan+linaro@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	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 02/10] dt-bindings: PCI: qcom: Do not require
 'msi-map-mask'
Message-ID: <20240216165406.GD39963@thinkpad>
References: <20240212165043.26961-1-johan+linaro@kernel.org>
 <20240212165043.26961-3-johan+linaro@kernel.org>
 <e396cf20-8598-4437-b635-09a4a737a772@linaro.org>
 <Zcy4Atjmb6-wofCL@hovoldconsulting.com>
 <59bd6e54-0d5d-4e1a-818a-475a96c223ff@linaro.org>
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On Wed, Feb 14, 2024 at 02:38:57PM +0100, Krzysztof Kozlowski wrote:
> On 14/02/2024 13:54, Johan Hovold wrote:
> > On Wed, Feb 14, 2024 at 01:01:20PM +0100, Krzysztof Kozlowski wrote:
> >> On 12/02/2024 17:50, Johan Hovold wrote:
> >>> Whether the 'msi-map-mask' property is needed or not depends on how the
> >>> MSI interrupts are mapped and it should therefore not be described as
> >>> required.
> >>
> >> I could imagine that on all devices the interrupts are mapped in a way
> >> you need to provide msi-map-mask. IOW, can there be a Qualcomm platform
> >> without msi-map-mask?
> > 
> > I don't have access to the documentation so I'll leave that for you guys
> > to determine. I do note that the downstream DT does not use it and that
> > we have a new devicetree in linux-next which also does not have it:
> > 
> > 	https://lore.kernel.org/r/20240125-topic-sm8650-upstream-pcie-its-v1-1-cb506deeb43e@linaro.org
> > 
> > But at least the latter looks like an omission that should be fixed.
> 
> Hm, either that or the mask for sm8450 was not needed as well. Anyway,
> thanks for explanation, appreciated!
> 

msi-map-mask is definitely needed as it would allow all the devices under the
same bus to reuse the MSI identifier. Currently, excluding this property will
not cause any issue since there is a single device under each bus. But we cannot
assume that is going to be the case on all boards.

I will submit a patch to fix SM8650.

- Mani

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