Hi Ard, On Wed, Feb 27, 2019 at 11:16:12AM +0100, Ard Biesheuvel wrote: > On Wed, 27 Feb 2019 at 11:02, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > > On 26/02/2019 23:28, Brian Norris wrote: > > > You're not the first person to notice this. All the motivations are not > > > necessarily painted clearly in their cover letter, but here are some > > > previous attempts at solving this problem: > > > > > > [RFC PATCH v11 0/5] PCI: rockchip: Move PCIe WAKE# handling into pci core > > > https://lkml.kernel.org/lkml/20171225114742.18920-1-jeffy.chen@xxxxxxxxxxxxxx/ > > > http://lkml.kernel.org/lkml/20171226023646.17722-1-jeffy.chen@xxxxxxxxxxxxxx/ > > > > > > As you can see by the 12th iteration, it wasn't left unsolved for lack > > > of trying... > > > > I wasn't aware of this. That's definitely a better approach than my > > hack, and I would really like this to be revived. > > > > I don't think this approach is entirely sound either. (I'm sure there may be problems with the above series. We probably should give it another shot though someday, as I think it's closer to the mark.) > From the side of the PCI device, WAKE# is just a GPIO line, and how it > is wired into the system is an entirely separate matter. So I don't > think it is justified to overload the notion of legacy interrupts with > some other pin that may behave in a way that is vaguely similar to how > a true wake-up capable interrupt works. I think you've conflated INTx with WAKE# just a bit (and to be fair, that's exactly what the bad binding we're trying to replace did, accidentally). We're not trying to claim this WAKE# signal replaces the typical PCI interrupts, but it *is* an interrupt in some sense -- "depending on your definition of interrupt", per our IRC conversation ;) > So I'd argue that we should add an optional 'wake-gpio' DT property > instead to the generic PCI device binding, and leave the interrupt > binding and discovery alone. So I think Mark Rutland already shot that one down; it's conceptually an interrupt from the device's perspective. We just need to figure out a good way of representing it that doesn't stomp on the existing INTx definitions. Brian
