Hi, Bjorn, On Sun, Jul 17, 2022 at 9:41 AM Jianmin Lv <lvjianmin@xxxxxxxxxxx> wrote: > > > > On 2022/7/17 上午7:32, Bjorn Helgaas wrote: > > On Sat, Jul 16, 2022 at 04:37:41PM +0800, Huacai Chen wrote: > >> On Sat, Jul 16, 2022 at 2:12 PM Jianmin Lv <lvjianmin@xxxxxxxxxxx> wrote: > >>> On 2022/7/16 上午11:23, Bjorn Helgaas wrote: > >>>> On Sat, Jul 16, 2022 at 10:27:00AM +0800, Jianmin Lv wrote: > >>>>> On 2022/7/16 上午12:37, Bjorn Helgaas wrote: > >>>>>> On Fri, Jul 15, 2022 at 04:05:12PM +0800, Jianmin Lv wrote: > >>>>>>> On 2022/7/15 上午11:44, Bjorn Helgaas wrote: > >>>>>>>> On Thu, Jul 14, 2022 at 08:42:16PM +0800, Huacai Chen wrote: > >>>>>>>>> From: Jianmin Lv <lvjianmin@xxxxxxxxxxx> > >>>>>>>>> > >>>>>>>>> In LS7A, multifunction device use same PCI PIN (because the > >>>>>>>>> PIN register report the same INTx value to each function) > >>>>>>>>> but we need different IRQ for different functions, so add a > >>>>>>>>> quirk to fix it for standard PCI PIN usage. > >>>>>>>>> > >>>>>>>>> This patch only affect ACPI based systems (and only needed > >>>>>>>>> by ACPI based systems, too). For DT based systems, the irq > >>>>>>>>> mappings is defined in .dts files and be handled by > >>>>>>>>> of_irq_parse_pci(). > >>>>>>>> > >>>>>>>> I'm sorry, I know you've explained this before, but I don't > >>>>>>>> understand yet, so let's try again. I *think* you're saying > >>>>>>>> that: > >>>>>>>> > >>>>>>>> - These devices integrated into LS7A all report 0 in their > >>>>>>>> Interrupt Pin registers. Per spec, this means they do not > >>>>>>>> use INTx (PCIe r6.0, sec 7.5.1.1.13). > >>>>>>>> > >>>>>>>> - However, these devices actually *do* use INTx. Function > >>>>>>>> 0 uses INTA, function 1 uses INTB, ..., function 4 uses > >>>>>>>> INTA, ... > >>>>>>>> > >>>>>>>> - The quirk overrides the incorrect values read from the > >>>>>>>> Interrupt Pin registers. > >>>>>>> > >>>>>>> Yes, right. > >>>>> > >>>>> Sorry, I didn't see the first item here carefully, so I have to > >>>>> correct it: all the integrated devices in 7A report 1 in PIN reg > >>>>> instead of 0. > >>>> > >>>>>>>> But I'm still confused about how loongson_map_irq() gets called. The > >>>>>>>> only likely path I see is here: > >>>>>>>> > >>>>>>>> pci_device_probe # pci_bus_type.probe > >>>>>>>> pci_assign_irq > >>>>>>>> pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin) > >>>>>>>> if (pin) > >>>>>>>> bridge->swizzle_irq(dev, &pin) > >>>>>>>> irq = bridge->map_irq(dev, slot, pin) > >>>>>>>> > >>>>>>>> where bridge->map_irq points to loongson_map_irq(). But > >>>>>>>> pci_assign_irq() should read 0 from PCI_INTERRUPT_PIN [1], so it > >>>>>>>> wouldn't call bridge->map_irq(). Obviously I'm missing something. > >>>>> > >>>>> Same thing, PCI_INTERRUPT_PIN reports 1, so bridge->map_irq() will be > >>>>> called. > >>>> > >>>> OK, that makes a lot more sense, thank you! > >>>> > >>>> But it does leave another question: the quirk applies to > >>>> DEV_PCIE_PORT_0 (0x7a09), DEV_PCIE_PORT_1 (0x7a19), and > >>>> DEV_PCIE_PORT_2 (0x7a29). > >>>> > >>>> According to the .dtsi [1], all those root ports are at function 0, > >>>> and if they report INTA, the quirk will also compute INTA. So why do > >>>> you need to apply the quirk for them? > >>> > >>> Oh, yes, I don't think they are required either. The fix is only > >>> required for multi-func devices of 7A. > >>> > >>> Huacai, we should remove PCIE ports from the patch. > >> > >> I agree to remove PCIE ports here. But since Bjorn has already merged > >> this patch, and the redundant devices listed here have no > >> side-effects, I suggest keeping it as is (but Bjorn is free to modify > >> if necessary). > > > > I'd be happy to update the branch to remove the devices mentioned > > (DEV_PCIE_PORT_x, DEV_LS7A_OHCI, DEV_LS7A_GPU). > > > > But the original patch [2] *only* listed DEV_PCIE_PORT_x, so I'm > > really confused about what's going on with them. I assume [2] fixed > > *something*, but now we're suggesting that we don't need it. > > > > [2] https://lore.kernel.org/all/20210514080025.1828197-5-chenhuacai@xxxxxxxxxxx/ > > > > Hi, Bjorn > > My original patch(obviously just for simple, unwilling to list so much > devices in the patch) is following; > > +static void loongson_pci_pin_quirk(struct pci_dev *dev) > +{ > + u8 fun = dev->devfn & 7; > + > + dev->pin = 1 + (fun & 3); > +} > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LOONGSON, PCI_ANY_ID, > loongson_pci_pin_quirk); > + > > Mybe Huacai think only PCIE ports need the fix, so he adds the PCIE > ports in the patch when submitting it. Yes, what Jianmin said is correct, the first version of my patch is wrong and the current version is correct. Huacai > > The things has been explained above, only multi-func devices are > required to fix. > > Thanks. >
