[patch 2/4] [ARM] mmp: support marvell ARMADA610

[Haojian Zhuang]

On Thu, Dec 31, 2009 at 10:46 PM, Eric Miao <eric.y.miao at gmail.com> wrote:
> On Thu, Dec 31, 2009 at 10:42 PM, Haojian Zhuang
> <haojian.zhuang at gmail.com> wrote:
>> On Mon, Dec 28, 2009 at 10:49 PM, Eric Miao <eric.y.miao at gmail.com> wrote:
>>> Haojian,
>>>
>>> Several suggestions:
>>>
>>> 1. entry-macro.S, could we simplify (and improve the performance a bit) to
>>> something like (haven't tested yet - let me know the result):
>>>
>>>        .macro  get_irqnr_preamble, base, tmp
>>>        mrc     p15, 0, \tmp, c0, c0, 0         @ CPUID
>>>        mov     \tmp, \tmp, lsr #4
>>>        and     \tmp, \tmp, #0xfff
>>
>> We shouldn't use #0xfff in and instruction. Immediate number shouldn't
>> beyond 8bit. We have to use ldr instruction or multiple instrunctions.
>
> Well, 0xff0 then, or ldr, whichever I don't mind.
>
>>
>>>        cmp     \tmp, #0x581                    @ MMP2
>>>        moveq   \base, #MMP2_ICU_PJ4_IRQ_SEL
>>>        movne   \base, #ICU_AP_IRQ_SEL_INT_NUM
>>>        .endm
>>>
>>>        .macro  arch_ret_to_user, tmp1, tmp2
>>>        .endm
>>>
>>>        .macro  get_irqnr_and_base, irqnr, irqstat, base, tmp
>>>        ldr     \tmp, [\base, #0]
>>>        and     \irqnr, \tmp, #0x3f             @ Interrupt Number
>>>        tst     \tmp, #(1 << 6)                 @ Interrupt Pending ?
>>>        .endm
>>>
>>
>> I don't like this way. Although more jump instructions are used in irq
>> entry, it can be extended easier for supporting more silicons.
>>
>
> It really hurt performance a lot. While the difference between MMP series
> is just the offset of the IRQ_NUM register, it could be calculated in
> get_irqnr_preamble, which doesn't have to be executed each time
> in the IRQ handling loop. See arch/arm/kernel/entry-armv.S

get_irqnr_preamble can only carries one base parameter and one tmp
parameter. base parameter is already used for interrupt control
register. Only one tmp parameter is left for use. If we want to check
chip id, one parameter is not enought.

So putting these code into get_irqnr_and_base macro is more reasonable.

Happy new year! :)

Best Regards
Haojian