On 12/09/16 23:02, Bjorn Helgaas wrote: > On Thu, Sep 01, 2016 at 05:19:55AM +0000, Bharat Kumar Gogada wrote: >>>>>>> Hi Bharat, >>>>>>>> @@ -561,7 +561,7 @@ static int nwl_pcie_init_irq_domain(struct >>>>>>>> nwl_pcie >>>>>>> *pcie) >>>>>>>> } >>>>>>>> >>>>>>>> pcie->legacy_irq_domain = irq_domain_add_linear(legacy_intc_node, >>>>>>>> - INTX_NUM, >>>>>>>> + INTX_NUM + 1, >>>>>>>> &legacy_domain_ops, >>>>>>>> pcie); >>>>>>> >>>>>>> This feels like the wrong thing to do. You have INTX_NUM irqs, so >>>>>>> the domain allocation should reflect this. On the other hand, the >>>>>>> way the driver currently deals with mappings is quite broken >>>>>>> (consistently adding 1 to >>>>> the HW interrupt). >>>>>>> >>>>>> Hi Marc, >>>>>> >>>>>> Without above change I get following crash in kernel while booting. >>>>>> >>>>>> [ 2.441684] error: hwirq 0x4 is too large for dummy >>>>>> >>>>>> [ 2.441694] ------------[ cut here ]------------ >>>>>> >>>>>> [ 2.441698] WARNING: at kernel/irq/irqdomain.c:344 >>>>>> >>>>>> [ 2.441702] Modules linked in: >>>>>> >>>>>> [ 2.441706] >>>>>> >>>>>> [ 2.441714] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.4.0 #8 >>>>>> >>>>>> [ 2.441718] Hardware name: xlnx,zynqmp (DT) >>>>>> >>>>>> [ 2.441723] task: ffffffc071886b80 ti: ffffffc071888000 task.ti: >>>>> ffffffc071888000 >>>>>> >>>>>> [ 2.441732] PC is at irq_domain_associate+0x138/0x1c0 >>>>>> >>>>>> [ 2.441738] LR is at irq_domain_associate+0x138/0x1c0 >>>>>> >>>>>> In kernel/irq/irqdomain.c function irq_domain_associate >>>>>> >>>>>> if (WARN(hwirq >= domain->hwirq_max, >>>>>> "error: hwirq 0x%x is too large for %s\n", (int)hwirq, domain- >>>> name)) >>>>>> return -EINVAL; >>>>>> >>>>>> Here the hwirq and hwirq_max are equal to 4 without the above >>>>>> condition >>>>> (INTX_NUM + 1) due to which crash is coming. >>>>>> This is happening as the legacy interrupts are starting from 1 (INTA). >>>>> >>>>> I understood that. I'm still persisting in saying that you have the wrong fix. >>>>> >>>>> Your domain should always allocate many interrupts as you have >>>>> interrupt sources. These interrupts (hwirq) should be numbered from 0 to (n- >>> 1). >>>> >>>> Agreed, but here comes the problem the hwirq for legacy interrupts >>>> will start at 0x1 to 0x4 (INTA to INTD) and these values are as per >>>> PCIe specification for legacy interrupts. So these cannot be numbered >>>> from 0. So when 0x4 (INTD) for a multi-function device comes the crash >>>> occurs. >>> >>> So who provides this hwirq? Who calls irq_domain_associate() with hwirq set to >>> 4? >>> >> PCIe subsystem invokes pcibios_add_device function in arch/arm64/kernel/pci.c for every pci device. >> The purpose of this function is to assign dev->irq using of_irq_parse_and_map_pci. >> of_irq_parse_and_map_pci invokes of_irq_parse_pci where it reads PCI_INTERRUPT_PIN from configuration space and saves it >> in parameter of struct of_phandle_args. >> This structure is passed to irq_create_of_mapping where it invokes irq_create_fwspec_mapping. >> irq_create_fwspec_mapping invokes irq_domain_translate and gets hwirq, here the above saved PCI_INTERRUPT_PIN value is assigned >> to hwirq (*hwirq = fwspec->param[0]). >> And then using this hwirq irq_create_mapping -> irq_domain_associate were invoked and mapping is created for virtual irq with this hwirq. >> So for any end point PCI_INTERRUPT_PIN value starts from 0x1 to 0x4 and so hwirq starts from 0x1 to 0x4. >> >> So the values are more generic w.r.t to protocol, that's why hwirq will range from 0x1 to 0x4. >> And then if you check pcie-altera.c they are doing this adding one in their handler and while creating legacy domain. > > Is this resolved yet? Marc, are you happy, or should we iterate on this > again? Ah, sorry to have dropped the ball on this patch. I guess that given that the infrastructure imposes the hwirq range on the host drivers, Bharat's approach is the only way (and a number of other host drivers are already slightly broken). I'll try and have a look at solving this at the generic level. In the meantime: Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx> Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
