On Wed, Mar 25, 2020 at 11:09:10PM +0800, Jiaxun Yang wrote: > > > 于 2020年3月25日 GMT+08:00 下午11:04:37, Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> 写到: > >On Wed, Mar 25, 2020 at 10:31:21PM +0800, Jiaxun Yang wrote: > >> > >> > >> 于 2020年3月25日 GMT+08:00 下午10:15:16, Marc Zyngier <maz@xxxxxxxxxx> 写到: > >> >On 2020-03-25 13:59, Jiaxun Yang wrote: > >> > > >> >[...] > >> > > >> >>>> So probably we can use legacy domain when MIPS IRQ BASE is in > >the > >> >>>> range of legacy IRQ > >> >>>> and switch to simple domain when it's not in that range? > >> >>> > >> >>> No, see below. > >> >>> > >> >>>> Here in Loongson systems IRQ 0-15 is occupied by I8259 so I did > >> >this > >> >>>> hack. > >> >>> > >> >>> Well, if you have to consider which Linux IRQ gets assigned, > >> >>> then your platform is definitely not ready for non-legacy > >> >>> irqdomains. Just stick to legacy for now until you have removed > >> >>> all the code that knows the hwirq mapping. > >> >> > >> >> Thanks. > >> >> > >> >> So I have to allocate irq_desc here in driver manually? > >> > > >> >No, you are probably better off just dropping this patch, as MIPS > >> >doesn't seem to be ready for a wholesale switch to virtual > >interrupts. > >> > >> It can't work without this patch. > >> > >> Legacy domain require IRQ number within 0-15 > >> however it's already occupied by i8259 or "HTPIC" driver. > > > >what's the problem here ? AFAIK there could be more than one > >legacy domain, at least that's what at least IP22/SNI in MIPS world > >are doing. > > MIPS_IRQ_BASE must be higher than 15, otherwise it will conflict with i8259. I still don't get it. We have following in arch/mips/include/asm/mach-generic/irq.h: #ifndef MIPS_CPU_IRQ_BASE #ifdef CONFIG_I8259 #define MIPS_CPU_IRQ_BASE 16 #else #define MIPS_CPU_IRQ_BASE 0 #endif /* CONFIG_I8259 */ #endif So every legacy platform with i8259 has MIPS_CPU_IRQ_BASE = 16. > However we have only preallocated irq_desc for 0-15. > And legacy domain require irq_desc being preallocated. maybe I'm too fast by judging the irq code, but without CONFIG_SPARSE_IRQ the whole irq_desc is pre-allocated. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]
