RE: [PATCH RFC NOT TESTED] PCI: intel-gw: Use use_parent_dt_ranges and clean up intel_pcie_cpu_addr_fixup()

From: Lei Chuan Hua
Date: Wed Mar 19 2025 - 02:11:12 EST

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In reply to: Bjorn Helgaas: "Re: [PATCH RFC NOT TESTED] PCI: intel-gw: Use use_parent_dt_ranges and clean up intel_pcie_cpu_addr_fixup()"
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> -----Original Message-----
> From: Bjorn Helgaas <helgaas@xxxxxxxxxx>
> Sent: Tuesday, 18 March 2025 11:32 pm
> To: Lei Chuan Hua <lchuanhua@xxxxxxxxxxxxx>
> Cc: Frank Li <Frank.Li@xxxxxxx>; Lorenzo Pieralisi
> <lpieralisi@xxxxxxxxxx>; Krzysztof Wilczyński <kw@xxxxxxxxx>; Manivannan
> Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>; Rob Herring
> <robh@xxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; linux-
> pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH RFC NOT TESTED] PCI: intel-gw: Use
> use_parent_dt_ranges and clean up intel_pcie_cpu_addr_fixup()
>
> This email was sent from outside of MaxLinear.
>
>
> On Tue, Mar 18, 2025 at 01:49:46AM +0000, Lei Chuan Hua wrote:
> > Hi Bjorn,
> >
> > I did a quick test with necessary change in dts. It worked, please
> move on.
>
> What does this mean? By "move on", do you mean that I should merge the
> patch below (the removal of intel_pcie_cpu_addr())?
I mean you can merge the patch with removal of intel_pcie_cpu_addr()

> I do not want to merge a change that will break any existing intel-gw
> platform. When you say "with necessary change in dts", it makes me
> think the removal of intel_pcie_cpu_addr() forces a change to dts, which
> would not be acceptable. We can't force users to upgrade the dts just
> to run a newer kernel.
>
Actually, intel_pcie_cpu_addr() did the address translation, so in our case,
Dts has to adapt to this change.
> I assume 250318 linux-next, which includes Frank's v12 series, should
> work with no change to dts required. (It would be awesome if you can
> verify that.)
>

I will try 250318 linux-next and let you know the result once it is done.

> If you apply this patch to remove intel_pcie_cpu_addr() on top of
> 250318 linux-next, does it still work with no changes to dts?
>
I think we need to adapt dts change. Even this series patch has dts
adaption part.

> If you have to make a dts change for it to work after removing
> intel_pcie_cpu_addr(), then we have a problem.
>
We can update the dts yaml file.
> I do not see a .dts file in the upstream tree that contains "intel,lgm-
> pcie", so I don't know what the .dts contains or how it is distributed.
>
> I do see the binding at
> Documentation/devicetree/bindings/pci/intel-gw-pcie.yaml,
> but the example there does not include anything about address
> translation between the CPU and the PCI controller, so my guess is that
> there are .dts files in the field that will not work if we remove
> intel_pcie_cpu_addr().
>
This driver is for x86 atom platform, no upstream dts file even in arch/x86/boot
Since upstream x86 platforms use acpi, even several platforms use dts, but
never create dts directory in arch/x86/boot.

As I mentioned earlier, dts needs a minor change.
> > ________________________________________
> > From: Bjorn Helgaas <mailto:helgaas@xxxxxxxxxx>
> > Sent: Tuesday, March 18, 2025 1:59 AM
> > To: Frank Li <mailto:Frank.Li@xxxxxxx>
> > Cc: Lei Chuan Hua <mailto:lchuanhua@xxxxxxxxxxxxx>; Lorenzo Pieralisi
> > <mailto:lpieralisi@xxxxxxxxxx>; Krzysztof Wilczyński <mailto:kw@xxxxxxxxx>;
> > Manivannan Sadhasivam <mailto:manivannan.sadhasivam@xxxxxxxxxx>; Rob Herring
> > <mailto:robh@xxxxxxxxxx>; Bjorn Helgaas <mailto:bhelgaas@xxxxxxxxxx>;
> > mailto:linux-pci@xxxxxxxxxxxxxxx <mailto:linux-pci@xxxxxxxxxxxxxxx>;
> > mailto:linux-kernel@xxxxxxxxxxxxxxx <mailto:linux-kernel@xxxxxxxxxxxxxxx>
> > Subject: Re: [PATCH RFC NOT TESTED] PCI: intel-gw: Use
> > use_parent_dt_ranges and clean up intel_pcie_cpu_addr_fixup()
> >
> >
> >
> > On Wed, Mar 05, 2025 at 12:07:54PM -0500, Frank Li wrote:
> > > Remove intel_pcie_cpu_addr_fixup() as the DT bus fabric should
> > > provide correct address translation. Set use_parent_dt_ranges to
> > > allow the DWC core driver to fetch address translation from the
> device tree.
> > >
> > > Signed-off-by: Frank Li <mailto:Frank.Li@xxxxxxx>
> >
> > Any update on this, Chuanhua?
> >
> > I plan to merge v12 of Frank's series [1] for v6.15. We need to know
> > ASAP if that would break intel-gw.
> >
> > If we knew that it was safe to also apply this patch to remove
> > intel_pcie_cpu_addr(), that would be even better.
> >
> > I will plan to apply the patch below on top of Frank's series [1] for
> > v6.15 unless I hear that it would break something.
> >
> > Bjorn
> >
> > [1]
> > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
> > .kernel.org%2Fr%2F20250315201548.858189-1-helgaas%40kernel.org&data=05
> > %7C02%7Clchuanhua%40maxlinear.com%7C1612d73ded5741bbd37508dd66320100%7
> > Cdac2800513e041b882807663835f2b1d%7C0%7C0%7C638779087153570342%7CUnkno
> > wn%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXa
> > W4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=aIuZWzwFy2r
> > rzsJ5KfbxWKMx%2BPn1WHx2KvpSR0nxsl8%3D&reserved=0
> >
> > > ---
> > > This patches basic on
> > > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flo
> > > re.kernel.org%2Fimx%2F20250128-pci_fixup_addr-v9-0-3c4bb506f665%40nx
> > > p.com%2F&data=05%7C02%7Clchuanhua%40maxlinear.com%7C1612d73ded5741bb
> > > d37508dd66320100%7Cdac2800513e041b882807663835f2b1d%7C0%7C0%7C638779
> > > 087153596851%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiI
> > > wLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C
> > > %7C%7C&sdata=mht19VSB24Znpvtz1pOlmtHYec%2BDBDH70zuLOZmwlSI%3D&reserv
> > > ed=0
> > >
> > > I have not hardware to test and there are not intel,lgm-pcie in
> > > kernel tree.
> > >
> > > Your dts should correct reflect hardware behavor, ref:
> > > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flo
> > > re.kernel.org%2Flinux-pci%2FZ8huvkENIBxyPKJv%40axis.com%2FT%2F%23mb7
> > > ae78c3a22324b37567d24ecc1c810c1b3f55c5&data=05%7C02%7Clchuanhua%40ma
> > > xlinear.com%7C1612d73ded5741bbd37508dd66320100%7Cdac2800513e041b8828
> > > 07663835f2b1d%7C0%7C0%7C638779087153612764%7CUnknown%7CTWFpbGZsb3d8e
> > > yJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiT
> > > WFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=DUsGCW%2FZpvx4whLteoIjYqw
> > > d6oOk9rXks%2BV40i5sovI%3D&reserved=0
> > >
> > > According to your intel_pcie_cpu_addr_fixup()
> > >
> > > Basically, config space/io/mem space need minus SZ_256. parent bus
> > > range convert it to original value.
> > >
> > > Look for driver owner, who help test this and start move forward to
> > > remove
> > > cpu_addr_fixup() work.
> > > ---
> > > Frank Li <mailto:Frank.Li@xxxxxxx>
> > > ---
> > > drivers/pci/controller/dwc/pcie-intel-gw.c | 8 +-------
> > > 1 file changed, 1 insertion(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pcie-intel-gw.c
> > > b/drivers/pci/controller/dwc/pcie-intel-gw.c
> > > index 9b53b8f6f268e..c21906eced618 100644
> > > --- a/drivers/pci/controller/dwc/pcie-intel-gw.c
> > > +++ b/drivers/pci/controller/dwc/pcie-intel-gw.c
> > > @@ -57,7 +57,6 @@
> > > PCIE_APP_IRN_INTA | PCIE_APP_IRN_INTB | \
> > > PCIE_APP_IRN_INTC | PCIE_APP_IRN_INTD)
> > >
> > > -#define BUS_IATU_OFFSET SZ_256M
> > > #define RESET_INTERVAL_MS 100
> > >
> > > struct intel_pcie {
> > > @@ -381,13 +380,7 @@ static int intel_pcie_rc_init(struct dw_pcie_rp
> *pp)
> > > return intel_pcie_host_setup(pcie); }
> > >
> > > -static u64 intel_pcie_cpu_addr(struct dw_pcie *pcie, u64 cpu_addr)
> > > -{
> > > - return cpu_addr + BUS_IATU_OFFSET;
> > > -}
> > > -
> > > static const struct dw_pcie_ops intel_pcie_ops = {
> > > - .cpu_addr_fixup = intel_pcie_cpu_addr,
> > > };
> > >
> > > static const struct dw_pcie_host_ops intel_pcie_dw_ops = { @@
> > > -409,6 +402,7 @@ static int intel_pcie_probe(struct platform_device
> *pdev)
> > > platform_set_drvdata(pdev, pcie);
> > > pci = &pcie->pci;
> > > pci->dev = dev;
> > > + pci->use_parent_dt_ranges = true;
> > > pp = &pci->pp;
> > >
> > > ret = intel_pcie_get_resources(pdev);
> > >
> > > ---
> > > base-commit: 1552be4855dacca5ea39b15b1ef0b96c91dbea0d
> > > change-id: 20250305-intel-7c25bfb498b1
> > >
> > > Best regards,
> > >

Next message: Sidong Yang: "[RFC PATCH v5 0/5] introduce io_uring_cmd_import_fixed_vec"
Previous message: Peter Chen: "Re: [PATCH 0/4] Loadable Module support for PCIe Cadence and J721E"
In reply to: Bjorn Helgaas: "Re: [PATCH RFC NOT TESTED] PCI: intel-gw: Use use_parent_dt_ranges and clean up intel_pcie_cpu_addr_fixup()"
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