On Mon, Jul 31, 2017 at 04:49:59PM -0700, Paul Burton wrote: > On Monday, 31 July 2017 16:36:08 PDT Bjorn Helgaas wrote: > > On Mon, Jul 31, 2017 at 04:19:13PM -0700, Paul Burton wrote: > > > Hi Bjorn, > > > > > > On Monday, 31 July 2017 15:58:22 PDT Bjorn Helgaas wrote: > > > > On Mon, Jul 24, 2017 at 11:49:22AM +0100, Paul Burton wrote: > > > > > Hi Guenter & all, > > > > > > > > > > On Monday, 24 July 2017 01:39:37 BST Guenter Roeck wrote: > > > > > > The MIPS Boston board configuration tries to enable > > > > > > CONFIG_PCIE_XILINX. > > > > > > That doesn't work since PCIE_XILINX depends on ARCH_ZYNQ || > > > > > > MICROBLAZE. > > > > > > Remove that restriction. > > > > > > > > > > I'd prefer that this patch does not go in standalone. The intent for > > > > > the > > > > > MIPS Boston board is that this driver is enabled for MIPS by this > > > > > patch: > > > > > > > > > > https://patchwork.kernel.org/patch/9794361/ > > > > > > > > > > But not until after earlier patches in that series fix issues with the > > > > > driver: > > > > > > > > > > https://patchwork.kernel.org/patch/9794355/ > > > > > https://patchwork.kernel.org/patch/9794357/ > > > > > https://patchwork.kernel.org/patch/9794359/ > > > > > > > > > > That has been held up by disagreement about whether the driver should > > > > > be > > > > > using 0-3 or 1-4 for hardware IRQ numbers, sadly, despite the driver > > > > > already being in tree & clearly broken, and my series not changing > > > > > which > > > > > the driver uses... > > > > > > > > It's true that your v5 series only changes xilinx from using hwirq 0-3 > > > > to 0-4 (with 0 being unused in both cases, and the addition of 4 > > > > fixing the "INTD doesn't work" bug). > > > > > > That isn't true - the xilinx-pcie driver already uses 1-4, and my change > > > simply prevents it from hitting a WARN() in the IRQ code when doing so. > > > > My apologies. I was relying on the changelog, which says the current > > code "creates an IRQ domain of size 4 (ie. IRQ numbers 0 through 3)" > > and the patch: > > > > - port->leg_domain = irq_domain_add_linear(pcie_intc_node, 4, > > + port->leg_domain = irq_domain_add_linear(pcie_intc_node, 1 + 4, > > > > I'm not enough of an IRQ expert to understand why what I said was > > incorrect (other than maybe INTD actually works, but emits a warning?) > > The driver does create an IRQ domain of size 4, as though it is going to use > numbering 0-3 with it. However the driver then goes on to use numbers 1-4, > which leads to a warning from the IRQ code because the domain isn't big enough > to cover the case where hwirq=4 (ie. INTD). > > It still works because irq_domain_associate() ends up inserting a mapping for > the IRQ into a radix tree rather than the linear_revmap array, but it's > clearly wrong that the driver creates a domain of size 4 & then uses hwirq=4, > hence the warnings. Does it really work? It looks like irq_domain_associate() returns -EINVAL after emitting the "error: hwirq 0x%x is too large for %s" warning, so it doesn't look like it would call radix_tree_insert(). > > > > However, I *would* like to see this issue cleaned up consistently > > > > across all our drivers. I mooted a couple ideas in [1], but nobody > > > > seemed interested. If I merged your series as-is, there would be even > > > > less interest. > > > > > > I've been travelling & haven't had time to look at any reworks as of yet, > > > but I do think the driver as-is is clearly broken & my fix is a pretty > > > obvious one, even if you would like the driver(s) to improve further in > > > future. > > > > My problem is that if all the drivers work because they use 5 numbers > > (0-4), the issue will completely drop off everybody's radar. > > I understand, and it's your call, but I'd argue that the driver as-is isn't > just suboptimal but plain broken - and I think that fixing it so that it's > "just" suboptimal is a worthwhile improvement that shouldn't be held up. But > you're the maintainer, and if you'd like to use this to bribe me or someone > else into improving things at some later date then so be it. This issue has been raised before. Each time it comes up it takes me a long time to re-figure out what's going on, and I'm sort of tired of doing that. Given that I have no budget or staff, my tools for getting things fixed are pretty limited, so I'm going to hold out for a more comprehensive fix here. Bjorn
