On Wed, 2010-03-24 at 17:44 +0000, Thomas Gleixner wrote: > On Wed, 24 Mar 2010, Ian Campbell wrote: > > > On Mon, 2010-03-22 at 10:19 +0000, Thomas Gleixner wrote: > > > On Sun, 21 Mar 2010, Yinghai Lu wrote: > > > > > > > From: Ian Campbell <ian.campb...@citrix.com> > > > > > > > > Move arch_init_copy_chip_data and arch_free_chip_data into function > > > > pointers in struct irq_chip since they operate on irq_desc->chip_data. > > > > > > Not sure about that. These functions are solely used by x86 and there > > > is really no need to generalize them. > > > > I thought the idea of struct irq_chip was to allow the potential for > > multiple IRQ controllers in a system? Given that it seems that struct > > irq_desc->chip_data ought to be available for use by whichever struct > > irq_chip is managing a given interrupt. At the moment this is not > > possible because we step around the abstraction using these arch_* > > methods. > > Right, but you have exactly _ONE_ irq_chip associated to an irq_desc, > but that same irq_chip can be associated to several irq_descs. So > irq_desc->data is there to provide data for the irq_chip functions > depending on what irq they handle (e.g. base_address ...). > > irq_desc->chip_data is set when the irq_chip is assigned to the > irq_desc. > > So there is no point in having functions in irq_chip to set > irq_desc->chip_data.
So how do you know which is the appropriate irq_chip specific function to call given an irq_desc that you want to copy/free/migrate? The contents of the chip_data pointer will take different forms for different irq_chips. The way the generic code is currently structured it appears you can't (or at least don't) just do a shallow copy by copying the irq_desc->chip_data pointer itself -- you need to do a deep copy using a function which understands that type of chip_data. How is this operation different to having pointers in irq_chip for enabling/disabling/masking interrupts for each irq_chip? Ian. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
