On 13/03/17 16:10, Mason wrote: > Hello, > > There are two revisions of our PCI Express controller. > > Rev 1 did not support the following features: > > 1) legacy PCI interrupt delivery (INTx signals) > 2) I/O address space > > Internally, someone stated that such missing support would prevent > some PCIe cards from working with our controller. > > Are there really modern PCIe cards that require 1) and/or 2) > to function? > > Can someone provide examples of such cards, so that I may test them > on both revisions? > > I was told to check ath9k-based cards. Any other examples? > > Looking around, I came across this thread: > http://lists.infradead.org/pipermail/linux-arm-kernel/2016-March/418254.html > "i.MX6 PCIe: Fix imx6_pcie_deassert_core_reset() polarity" > > IIUC, although some PCIe boards do support MSI, the driver might not > put in the work to use that infrastructure, and instead reverts to > legacy interrupts. (So it is a SW issue, in a sense.) Secondary to that category is endpoints which nominally support MSI, but in a way which is unreliable or otherwise broken. My experience shows that the Silicon Image SiI 3132 (as integrated on ARM Juno boards, but seemingly also relatively common on 'generic' 2-port SATA cards) falls into that category - using the command-line parameter to force MSIs instead of legacy interrupts leads to the the machine barely reaching userspace before something goes horribly wrong: ... Activating swap Swap Partition... [ 10.817806] Adding 524284k swap on /dev/sda2. Priority:-1 extents:1 across:524284k SS Starting File System Check on /dev/disk/by-uuid/1000-9346... [ OK ] Activated swap Swap Partition. [ OK ] Activated swap /dev/disk/by-partuui…6cda4-9f73-4e26-bf19-e71f9319b5ce. [ OK ] Reached target Swap. Mounting Temporary Directory... [ OK ] Mounted Temporary Directory. [ OK ] Started File System Check on /dev/disk/by-uuid/1000-9346. [ 46.036065] Unhandled fault: synchronous external abort (0x96000210) at 0xffff0000092f5000 [ 46.044273] Internal error: : 96000210 [#1] PREEMPT SMP [ 46.049445] Modules linked in: [ 46.052474] CPU: 0 PID: 122 Comm: scsi_eh_0 Not tainted 4.11.0-rc1+ #1753 [ 46.059192] Hardware name: ARM Juno development board (r1) (DT) [ 46.065052] task: ffff8009763b8000 task.stack: ffff800975f70000 [ 46.070918] PC is at ata_wait_register+0x2c/0xa0 [ 46.075491] LR is at sil24_init_port+0x60/0x110 [ 46.079974] pc : [<ffff0000085b342c>] lr : [<ffff0000085d2b78>] pstate: 40000145 ... Robin.
