On Tue, Jul 21, 2015 at 11:58:01PM +0200, Thomas Gleixner wrote: > On Tue, 21 Jul 2015, Florian Fainelli wrote: > > On 21/07/15 14:23, Thomas Gleixner wrote: > > > I just read back on the problem report which was mentioned in the > > > changelog: > > > > > > "It's not a problem with patch 7, exactly, it's a problem with the > > > irqchip driver which handles the UART interrupt mask (irq-bcm7120-l2.c). > > > The problem is that with a trimmed down device tree (such as the one > > > found at arch/arm/boot/dts/bcm7445-bcm97445svmb.dtb), none of the child > > > interrupts of the 'irq0_intc' node are described -- we don't have device > > > tree nodes for them yet -- but we still require saving and restoring the > > > forwarding mask (see 'brcm,int-fwd-mask') in order for the UART > > > interrupts to continue operating." > > > > > > So you are trying to work around a flaw in the device tree by adding > > > random callbacks to the core kernel? > > > > Not quite, you could have your interrupt controller node declared in > > Device Tree, but have no "interrupts" property referencing it because: > > > > - the hardware is just not there, but you inherit a common Device Tree > > skleten (*.dtsi) > > - you could have Device Tree overlays which may or may not be loaded as > > a result of finding expansion boards etc... > > So if no hardware is there which uses any of those interrupts, then > WHY is it a problem at all? This particular badly-designed L2 interrupt controller not only configures its own constituent interrupts, but it controls whether some interrupts are seen at level 1 (e.g., GIC), rather than L2. So some interrupts are affected, but not owned, by this hardware (and driver). > If it's a requirement that these registers must be restored (once, not > per irq), then I can see that it'd be nice to do that from the core. Right, they must be restored for the whole chip. > Though that core suspend/resume function is generic chip specific. So > it does not make any sense to force it into struct irq_chip because we > have no core infrastructure to deal with it. Right, and that's what v2 does. Thanks for the comments. Brian
