Re: [PATCH] arm64: dts: qcom: qcs6490-rb3gen2: Add PCIe nodes
From: Krishna Chaitanya Chundru
Date: Fri Oct 11 2024 - 07:55:02 EST
On 10/1/2024 8:38 PM, Dmitry Baryshkov wrote:
On October 1, 2024 5:19:48 PM GMT+03:00, Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> wrote:
On Tue, Oct 01, 2024 at 03:30:14PM +0300, Dmitry Baryshkov wrote:
On October 1, 2024 1:16:22 PM GMT+03:00, Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> wrote:
On Fri, Feb 09, 2024 at 12:56:18PM +0200, Dmitry Baryshkov wrote:
On Fri, 9 Feb 2024 at 09:57, Manivannan Sadhasivam
<manivannan.sadhasivam@xxxxxxxxxx> wrote:
On Fri, Feb 09, 2024 at 12:58:15PM +0530, Krishna Chaitanya Chundru wrote:
On 2/8/2024 8:49 PM, Dmitry Baryshkov wrote:
On Thu, 8 Feb 2024 at 16:58, Krishna Chaitanya Chundru
<quic_krichai@xxxxxxxxxxx> wrote:
On 2/8/2024 12:21 PM, Dmitry Baryshkov wrote:
On Thu, 8 Feb 2024 at 08:14, Krishna Chaitanya Chundru
<quic_krichai@xxxxxxxxxxx> wrote:
On 2/7/2024 5:17 PM, Dmitry Baryshkov wrote:
On Wed, 7 Feb 2024 at 12:42, Krishna chaitanya chundru
<quic_krichai@xxxxxxxxxxx> wrote:
Enable PCIe1 controller and its corresponding PHY nodes on
qcs6490-rb3g2 platform.
PCIe switch is connected to PCIe1, PCIe switch has multiple endpoints
connected. For each endpoint a unique BDF will be assigned and should
assign unique smmu id. So for each BDF add smmu id.
Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts | 42 ++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
index 8bb7d13d85f6..0082a3399453 100644
--- a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
+++ b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
@@ -413,6 +413,32 @@ vreg_bob_3p296: bob {
};
};
+&pcie1 {
+ perst-gpios = <&tlmm 2 GPIO_ACTIVE_LOW>;
+
+ pinctrl-0 = <&pcie1_reset_n>, <&pcie1_wake_n>;
+ pinctrl-names = "default";
+
+ iommu-map = <0x0 &apps_smmu 0x1c80 0x1>,
+ <0x100 &apps_smmu 0x1c81 0x1>,
+ <0x208 &apps_smmu 0x1c84 0x1>,
+ <0x210 &apps_smmu 0x1c85 0x1>,
+ <0x218 &apps_smmu 0x1c86 0x1>,
+ <0x300 &apps_smmu 0x1c87 0x1>,
+ <0x400 &apps_smmu 0x1c88 0x1>,
+ <0x500 &apps_smmu 0x1c89 0x1>,
+ <0x501 &apps_smmu 0x1c90 0x1>;
Is the iommu-map really board specific?
The iommu-map for PCIe varies if PCIe switch is connected.
For this platform a PCIe switch is connected and for that reason
we need to define additional smmu ID's for each BDF.
For that reason we defined here as these ID's are applicable only
for this board.
So, these IDs are the same for all boards, just being unused on
devices which have no bridges / switches connected to this PCIe host.
If this is correct, please move them to sc7280.dtsi.
Yes ID's will be same for all boards. we can move them sc7280.dtsi
but the BDF to smmu mapping will be specific to this board only.
if there is some other PCIe switch with different configuration is
connected to different board of same variant in future again these
mapping needs to updated.
Could you possibly clarify this? Are they assigned one at a time
manually? Or is it somehow handled by the board's TZ code, which
assigns them sequentially to the known endpoints? And is it done via
probing the link or via some static configuration?
There is no assignment of SID's in TZ for PCIe.
PCIe controller has BDF to SID mapping table which we need to
program with the iommu map table.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/dwc/pcie-qcom.c?h=v6.8-rc3#n997
Based upon switch the BDF to SID table will change for example I had two
switches with one switch has 2 PCIe ports and other has 3 ports one
embedded port which supports multiple functions.
For the first switch the BDF's are
- 0x000(root complex),
- 0x100(USP),
- 0x208(DSP 0),
- 0x210(DSP 1),
- 0x300(endpoint connected to DSP 0),
- 0x400( endpoint connected to DSP 1).
For 2nd switch the BDF's are
- 0x000(root complex),
- 0x100(USP),
- 0x208(embeeded DSP 0),
- 0x210(DSP 1),
- 0x218 (DSP 2),
- 0x300(embedded endpoint function 0),
- 0x301 (embedded endpoint function 1)
- 0x400( endpoint connected to DSP 1)
- 0x500(endpoint connected to DSP2).
For these two switches we need different BDF to SID table so for that
reason we are keeping iommu map here as this is specific to this board.
I don't understand why the SID table has to change between PCIe devices. The SID
mapping should be part of the SoC dtsi, where a single SID would be defined for
the devices under a bus. And all the devices under the bus have to use the same
SID.
This sounds like a sane default, indeed. Nevertheless, I see a point
in having per-device-SID assignment. This increases isolation and can
potentially prevent security issues. However in such case SID
assignment should be handled in some automagic way. In other words,
there must be no need to duplicate the topology of the PCIe bus in the
iommu-maps property.
Agree with you on this. This is what I suggested some time back to have the
logic in the SMMU/PCIe drivers to assign SIDs dynamically. Unfortunately, it is
not a trivial work and it requires a broader discussion with the community.
Also starting with SMMUv3, there are practically no limitations in SIDs and
each device should get a unique SID by default.
So I got convinced that we can have these static mappings in the DT *atm* for
non SMMUv3 based hardwares and at the same time let the discussion happen with
the community. But this static mapping solution is just an interim one and won't
scale if more devices are added to the topology.
e
My main question to this approach is if it can support additional devices plugged into the switch. If there is no way to plug addon cards, then it is fine as a temporary measure.
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.
- Krishna chaitanya.
variant doesn't expose any open slots >
- Mani