On Thu, Dec 9, 2021 at 5:35 AM Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx> wrote: > > Hi Rob and Marc, > > On Thu, Dec 9, 2021 at 10:33 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > On Thu, 09 Dec 2021 10:00:44 +0000, > > "Lad, Prabhakar" <prabhakar.csengg@xxxxxxxxx> wrote: > > > > > > > The root of the issue is that all the resource allocation is done > > > > upfront, way before we even have a driver that could potentially > > > > deal with this device. This is a potential waste of resource, and > > > > it triggers the issue you noticed. > > > > > > > > If you delay the resource allocation until there is an actual > > > > match with a driver, you could have a per-driver flag telling you > > > > whether the IRQ allocation should be performed before the probe() > > > > function is called. > > > > > > > As suggested by Rob, if we switch the drivers to use > > > platform_get_resource(pdev, IORESOURCE_IRQ, n) call with > > > platform_get_irq() this code should go away and with this switch the > > > resource allocation will happen demand. Is this approach OK? > > > > If you get rid of of_irq_to_resource_table() altogether, then yes, > > this has a fighting chance to work. > > > Yes, switching to platform_get_irq() will eventually cause > of_irq_to_resource_table() to go away. > > On second thought, instead of touching all the drivers, if we update > platform_get_resource/platform_get_resource_byname to internally call > platform_get_irq() internally if it's a IORESOURCE_IRQ resource. Does > that sound good or should I just get on changing all the drivers to > use platform_get_irq() instead? Except that platform_get_irq() already internally calls platform_get_resource()... I think changing the drivers is the right way. Happy to do some if you want to divide it up. Using coccigrep, I think I've found all the places using platform_device.resource directly. A large swath are Sparc drivers which don't matter. The few that do matter I've prepared patches for here[1]. Most of what I found were DT based drivers that copy resources to a child platform device. That case will not work with platform_get_irq() callers either unless the child device has it's DT node set to the parent node which is the change I made. Rob [1] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-kernelci
