linux-kernel - RE: [PATCH RFC NOT TESTED] PCI: intel-gw: Use use_parent_dt_ranges and clean up intel_pcie_cpu_addr

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Message-ID:
 <BY3PR19MB507667CE7531D863E1E5F8AEBDD82@BY3PR19MB5076.namprd19.prod.outlook.com>
Date: Thu, 20 Mar 2025 02:44:15 +0000
From: Lei Chuan Hua <lchuanhua@...linear.com>
To: Bjorn Helgaas <helgaas@...nel.org>
CC: Frank Li <Frank.Li@....com>, Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>, Manivannan Sadhasivam
	<manivannan.sadhasivam@...aro.org>, Rob Herring <robh@...nel.org>, Bjorn
 Helgaas <bhelgaas@...gle.com>, "linux-pci@...r.kernel.org"
	<linux-pci@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH RFC NOT TESTED] PCI: intel-gw: Use use_parent_dt_ranges
 and clean up intel_pcie_cpu_addr_fixup()



> -----Original Message-----
> From: Bjorn Helgaas <helgaas@...nel.org>
> Sent: Thursday, 20 March 2025 3:23 am
> To: Lei Chuan Hua <lchuanhua@...linear.com>
> Cc: Frank Li <Frank.Li@....com>; Lorenzo Pieralisi
> <lpieralisi@...nel.org>; Krzysztof Wilczyński <kw@...ux.com>; Manivannan
> Sadhasivam <manivannan.sadhasivam@...aro.org>; Rob Herring
> <robh@...nel.org>; Bjorn Helgaas <bhelgaas@...gle.com>; linux-
> pci@...r.kernel.org; linux-kernel@...r.kernel.org
> 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 19, 2025 at 06:10:57AM +0000, Lei Chuan Hua wrote:
> > > -----Original Message-----
> > > From: Bjorn Helgaas <helgaas@...nel.org>
> > > Sent: Tuesday, 18 March 2025 11:32 pm
> > > To: Lei Chuan Hua <lchuanhua@...linear.com>
> > > Cc: Frank Li <Frank.Li@....com>; Lorenzo Pieralisi
> > > <lpieralisi@...nel.org>; Krzysztof Wilczyński <kw@...ux.com>;
> > > Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>; Rob
> > > Herring <robh@...nel.org>; Bjorn Helgaas <bhelgaas@...gle.com>;
> > > linux- pci@...r.kernel.org; linux-kernel@...r.kernel.org
> > > 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.
> 
> If there are end users that have a dts that must be changed before
> intel_pcie_cpu_addr() can be removed, we can't remove it because we
> can't force those users to upgrade their dts.
> 
> If this driver is only used internally to Intel, or if the hardware has
> never been shipped to end users, it's OK to remove
> intel_pcie_cpu_addr() and assume those internal users will update dts.

This driver is only used for internally to Maxlinear. Internal users will update dts
Accordingly. Anyway, we will take linux-next-20250318 to run the test with dts adaptation
Internally on the hardware board.
> 
> > > > ________________________________________
> > > > From: Bjorn Helgaas <mailto:helgaas@...nel.org>
> > > > Sent: Tuesday, March 18, 2025 1:59 AM
> > > > To: Frank Li <mailto:Frank.Li@....com>
> > > > Cc: Lei Chuan Hua <mailto:lchuanhua@...linear.com>; Lorenzo
> > > > Pieralisi <mailto:lpieralisi@...nel.org>; Krzysztof Wilczyński
> > > > <mailto:kw@...ux.com>; Manivannan Sadhasivam
> > > > <mailto:manivannan.sadhasivam@...aro.org>; Rob Herring
> > > > <mailto:robh@...nel.org>; Bjorn Helgaas
> > > > <mailto:bhelgaas@...gle.com>; mailto:linux-pci@...r.kernel.org
> > > > <mailto:linux-pci@...r.kernel.org>;
> > > > mailto:linux-kernel@...r.kernel.org
> > > > <mailto:linux-kernel@...r.kernel.org>
> > > > 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@....com>
> > > >
> > > > 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%2F
> > > > lore%2F&data=05%7C02%7Clchuanhua%40maxlinear.com%7C1c7a4180ddc340f
> > > > 2399308dd671b6e6a%7Cdac2800513e041b882807663835f2b1d%7C0%7C0%7C638
> > > > 780089712963723%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIl
> > > > YiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D
> > > > %7C0%7C%7C%7C&sdata=ESUTIdyb342xMYwUhzwj%2BXsKoNQzth86rV3dfis5dn0%
> > > > 3D&reserved=0
> > > > .kernel.org%2Fr%2F20250315201548.858189-1-helgaas%40kernel.org&dat
> > > > a=05
> > > > %7C02%7Clchuanhua%40maxlinear.com%7C1612d73ded5741bbd37508dd663201
> > > > 00%7
> > > > Cdac2800513e041b882807663835f2b1d%7C0%7C0%7C638779087153570342%7CU
> > > > nkno
> > > > wn%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiO
> > > > iJXa
> > > > W4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=aIuZWzw
> > > > Fy2r
> > > > rzsJ5KfbxWKMx%2BPn1WHx2KvpSR0nxsl8%3D&reserved=0
> > > >
> > > > > ---
> > > > > This patches basic on
> > > > > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%
> > > > > 2Flo%2F&data=05%7C02%7Clchuanhua%40maxlinear.com%7C1c7a4180ddc34
> > > > > 0f2399308dd671b6e6a%7Cdac2800513e041b882807663835f2b1d%7C0%7C0%7
> > > > > C638780089712987168%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRy
> > > > > dWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoy
> > > > > fQ%3D%3D%7C0%7C%7C%7C&sdata=PguxNdlqlw4e%2FqmgY4aM67UarmNDwx7RCV
> > > > > 69x0myXJc%3D&reserved=0
> > > > > re.kernel.org%2Fimx%2F20250128-pci_fixup_addr-v9-0-3c4bb506f665%
> > > > > 40nx
> > > > > p.com%2F&data=05%7C02%7Clchuanhua%40maxlinear.com%7C1612d73ded57
> > > > > 41bb
> > > > > d37508dd66320100%7Cdac2800513e041b882807663835f2b1d%7C0%7C0%7C63
> > > > > 8779
> > > > > 087153596851%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlY
> > > > > iOiI
> > > > > wLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C
> > > > > 0%7C
> > > > > %7C%7C&sdata=mht19VSB24Znpvtz1pOlmtHYec%2BDBDH70zuLOZmwlSI%3D&re
> > > > > serv
> > > > > 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%2F&data=05%7C02%7Clchuanhua%40maxlinear.com%7C1c7a4180ddc34
> > > > > 0f2399308dd671b6e6a%7Cdac2800513e041b882807663835f2b1d%7C0%7C0%7
> > > > > C638780089713001616%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRy
> > > > > dWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoy
> > > > > fQ%3D%3D%7C0%7C%7C%7C&sdata=DyXeezC8qsW2cdRg37sKVq2AH82vCV7L7YJ%
> > > > > 2FtgH6jU0%3D&reserved=0
> > > > > re.kernel.org%2Flinux-pci%2FZ8huvkENIBxyPKJv%40axis.com%2FT%2F%2
> > > > > 3mb7
> > > > > ae78c3a22324b37567d24ecc1c810c1b3f55c5&data=05%7C02%7Clchuanhua%
> > > > > 40ma
> > > > > xlinear.com%7C1612d73ded5741bbd37508dd66320100%7Cdac2800513e041b
> > > > > 8828
> > > > > 07663835f2b1d%7C0%7C0%7C638779087153612764%7CUnknown%7CTWFpbGZsb
> > > > > 3d8e
> > > > > yJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOI
> > > > > joiT
> > > > > WFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=DUsGCW%2FZpvx4whLteoI
> > > > > jYqw
> > > > > 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@....com>
> > > > > ---
> > > > >  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,
> > > > >