RE: [PATCH v3 2/2] pci/aer: interrupt fixup in the quirk

Po Liu
2016-09-21T11:25:09Z

Hi Bjorn,

> -----Original Message-----
> From: Bjorn Helgaas [mailto:helgaas@kernel.org]
> Sent: Wednesday, September 21, 2016 4:47 AM
> To: Po Liu
> Cc: Roy Zang; Arnd Bergmann; devicetree@vger.kernel.org; Marc Zyngier;
> linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org; Stuart Yoder;
> M.H. Lian; Murali Karicheri; Mingkai Hu; Bjorn Helgaas; Leo Li; Shawn
> Guo; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH v3 2/2] pci/aer: interrupt fixup in the quirk
>
> On Mon, Aug 22, 2016 at 10:09:18AM +0000, Po Liu wrote:
> > Hi Bjorn,
> >
> > Sorry for late reply.
> >
> > I checked the updated kernel with Dongdong mentioned ACPI patch which
> was truly affected my quirk patch uploaded. So I suppose the quirk patch
> is not qualify to fix the bug.
>
> I don't understand what you're saying here.
>
> The quirk worked on your machine. It apparently didn't work on
> Dongdong's machine because of_irq_parse_and_map_pci() is run after the
> quirk in this path:
>
> pci_device_probe
> pcibios_alloc_irq # arm64
> dev->irq = of_irq_parse_and_map_pci
>
> and of_irq_parse_and_map_pci() returned zero, probably because
> of_irq_parse_pci() failed. My guess is that the reason it works on your
> machine but not Dongdong's is that your DTs are different such that
> of_irq_parse_pci() works for you but not for Dongdong.
>
> I think the idea of of_irq_parse_and_map_pci() is to set up a device's
> INTx line. But that doesn't quite apply here because your device
> doesn't actually *use* INTx. So I don't know why of_irq_parse_pci()
> works for you. Maybe that's a symptom of a problem in your DT.
>
> Or maybe you're saying that the quirk *didn't* work on your machine when
> you tested it in a kernel that included d8ed75d59332 ("ARM64:
> PCI: ACPI support for legacy IRQs parsing and consolidation with DT
> code").

Yes, this point is what I mean. After this patch my quirk patch would not work.
Since I discussed with Dongdong, the patches d8ed75d59332 ACPI related were not be merged yet.

> But that doesn't make sense either, because prior to
> d8ed75d59332, we *always* set
>
> dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
>
> and after the patch we only do it if "acpi_disabled". I guess I just
> don't understand what you're saying.

Before the patch merged. pcibios_add_device()(which run the ->irq = of_irq_parse_and_map_pci(dev, 0, 0);) was loaded before the pci_fixup_device(pci_fixup_final).
But after the patch d8ed75d59332("ARM64: PCI: ACPI support for legacy IRQs parsing and consolidation with DT code") merged, the pci_fixup_device(pci_fixup_final) run BEFORE the pcibios_alloc_irq()(which run the ->irq = of_irq_parse_and_map_pci(dev, 0, 0);). So the dev->irq were overwhelm by the pcibios_alloc_irq().

When I test, the acpi_disabled is '1' although my kernel config default is CONFIG_ACPI=y. And no setting in the uboot with apci=xxx. But this is another issue, I didn't deep to check it.

>
> > I were keep thinking what your "explicitly checking for a root port
> device" meaning. Do you mean I should upload again the first version
> patch which fix it in the portdrv_core.c ? I would upload again if yes.
>
> No, I did not mean you should go back to the first version of the patch.
> If we *can* do this in a quirk, I think that would be much better than
> doing it in the PCIe port driver. I meant that Dongdong's suggestion of
> adding this:
>
> if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT)
> return;
>
> to your quirk made sense to me.

If the quirk patch could make workaround. It should be the better way.

Po Liu

>
> > > -----Original Message-----
> > > From: Bjorn Helgaas [mailto:helgaas@kernel.org]
> > > Sent: Saturday, July 30, 2016 6:42 AM
> > > To: Po Liu
> > > Cc: linux-pci@vger.kernel.org;
> > > linux-arm-kernel@lists.infradead.org;
> > > linux-kernel@vger.kernel.org; devicetree@vger.kernel.org; Roy Zang;
> > > Arnd Bergmann; Marc Zyngier; Stuart Yoder; Yang-Leo Li; Minghuan
> > > Lian; Murali Karicheri; Bjorn Helgaas; Shawn Guo; Mingkai Hu
> > > Subject: Re: [PATCH v3 2/2] pci/aer: interrupt fixup in the quirk
> > >
> > > On Tue, Jun 14, 2016 at 04:24:05PM +0800, Po Liu wrote:
> > > > On some platforms, root port doesn't support MSI/MSI-X/INTx in RC
> mode.
> > > > When chip support the aer interrupt with none MSI/MSI-X/INTx
> > > mode, > maybe there is interrupt line for aer pme etc. Search the
> > > interrupt > number in the fdt file. Then fixup the dev->irq with it.
> > > >
> > > > Signed-off-by: Po Liu <po.liu@nxp.com>
> > >
> > > I'm not sure where we're at with this. Dongdong had some issue
> > > (possibly with a version of the quirk on a different platform?), and
> > > I think the suggestion of explicitly checking for a root port
> > > device was a good one.
> > >
> > > So please update and repost this for next cycle.
> > >
> > > > ---
> > > > changes for V3:
> > > > - Move to quirk;
> > > > - Only correct the irq in RC mode;
> > > >
> > > > drivers/pci/quirks.c | 29 +++++++++++++++++++++++++++++ > 1
> > > file changed, 29 insertions(+) > > diff --git
> > > a/drivers/pci/quirks.c b/drivers/pci/quirks.c index >
> > > ee72ebe..8b39cce 100644 > --- a/drivers/pci/quirks.c > +++
> > > b/drivers/pci/quirks.c > @@ -25,6 +25,7 @@ > #include
> > > <linux/sched.h> > #include <linux/ktime.h> > #include
> > > <linux/mm.h> > +#include <linux/of_irq.h>
> > > > #include <asm/dma.h> /* isa_dma_bridge_buggy */
> > > > #include "pci.h"
> > > >
> > > > @@ -4419,3 +4420,31 @@ static void quirk_intel_qat_vf_cap(struct
> > > pci_dev *pdev)
> > > > }
> > > > }
> > > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x443, >
> > > quirk_intel_qat_vf_cap); > + > +/* If root port doesn't support
> > > MSI/MSI-X/INTx in RC mode, > + * but use standalone irq. Read the
> > > device tree for the aer > + * interrupt number.
> > > > + */
> > > > +static void quirk_aer_interrupt(struct pci_dev *dev) {
> > > > + int ret;
> > > > + u8 header_type;
> > > > + struct device_node *np = NULL;
> > > > +
> > > > + /* Only for the RC mode device */
> > > > + pci_read_config_byte(dev, PCI_HEADER_TYPE, &header_type);
> > > > + if ((header_type & 0x7F) != PCI_HEADER_TYPE_BRIDGE)
> > > > + return;
> > > > +
> > > > + if (dev->bus->dev.of_node)
> > > > + np = dev->bus->dev.of_node;
> > > > +
> > > > + if (IS_ENABLED(CONFIG_OF_IRQ) && np) {
> > > > + ret = of_irq_get_byname(np, "aer");
> > > > + if (ret > 0) {
> > > > + dev->no_msi = 1;
> > > > + dev->irq = ret;
> > > > + }
> > > > + }
> > > > +}
> > > > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, >
> > > +quirk_aer_interrupt); > -- > 2.1.0.27.g96db324 > > >
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