linux-kernel - Re: [PATCH] arm64: dts: qcom: qcs6490-rb3gen2: Add PCIe nodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241022151005.g36xnr7lf46p32ha@thinkpad>
Date: Tue, 22 Oct 2024 20:40:05 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
	quic_nitegupt@...cinc.com, quic_skananth@...cinc.com,
	quic_parass@...cinc.com
Subject: Re: [PATCH] arm64: dts: qcom: qcs6490-rb3gen2: Add PCIe nodes

On Thu, Oct 17, 2024 at 02:12:00PM +0300, Dmitry Baryshkov wrote:
> On Wed, Oct 16, 2024 at 10:43:19AM +0530, Krishna Chaitanya Chundru wrote:
> > 
> > 
> > On 10/14/2024 4:55 AM, Dmitry Baryshkov wrote:
> > > On Sat, Oct 12, 2024 at 06:13:34PM +0530, Manivannan Sadhasivam wrote:
> > > > On Fri, Oct 11, 2024 at 05:24:29PM +0530, Krishna Chaitanya Chundru wrote:
> > > > 
> > > > [...]
> > > > 
> > > > > > > The logic here is that the fixed endpoints in the switch will get an unique SID
> > > > > > > and the devices getting attached to slots will share the same SID of the bus
> > > > > > > (this is the usual case with all Qcom SoCs).
> > > > > > > 
> > > > > > > But I guess we would need 'iommu-map-mask' as well. Hope this addresses your
> > > > > > > concern.
> > > > > > 
> > > > > > Yes, thank you!
> > > > > > 
> > > > > Hi dimitry & mani,
> > > > > 
> > > > > This particular board variant doesn't expose any open slots to connect
> > > > > a different endpoints like another switch(which might have BDF unknown
> > > > > to us) so static table should be fine for this board variant.
> > > > > 
> > > > > I tries to add iommu-map-mask property, the issue with that property is
> > > > > that the driver is applying the mask to the bdf before searching for the
> > > > > entry in the table. If I use a mask value which satisfies all the
> > > > > entries in the table ( mask as 0x718) and if a new bdf is enumerated
> > > > > lets say 0x600 due to mask 0x718 its value is again 0x600 only.
> > > > > 
> > > > > Can we skip iommu-map-mask property and use only static table for this
> > > > > board as we know this board doesn't expose any open slots.
> > > > > 
> > > > 
> > > > Hmm, I was not aware that it doesn't have open slots. Fine with me then.
> > > 
> > > It doesn't feature open slots, but it has two PCIe connections on HS2 /
> > > HS3. Users might attach external PCIe devices.
> > > 
> > > Krishna, could you please clarify, how those two connections are routed?
> > > 
> > For this qps615 board to one of the downstream port (pcie to usb) usb
> > hub is connected and to the other downstream port NVMe will be
> > connected.
> 
> The board has two PCIe links routed to the HS2 and HS3 connectors. Are
> they routed to the PCIe switch?
> 
> Yes, they are not standard slots, but still the board is expandable and
> it is possible to connect external PCIe devices. As such it is not
> possible to have static SID mapping.
> 

Sorry, I think the conversation got deviated. We have concluded that the
endpoints fixed (soldered) in the board will get a fixed SID (because we know
what they are) and all other devices going to get connected to HS/LS connectors
will get shared SID (because we don't know what they are).

Any concern with that?

- Mani

-- 
மணிவண்ணன் சதாசிவம்