[PATCH 9/9] ARM: pxa: add iwmmx support for PJ4

[Haojian Zhuang]

>-----Original Message-----
>From: Nicolas Pitre [mailto:nico at fluxnic.net]
>Sent: 2010年11月17日 11:56 PM
>To: Haojian Zhuang
>Cc: linux-arm-kernel at lists.infradead.org; Zhou Zhu; Eric Miao
>Subject: RE: [PATCH 9/9] ARM: pxa: add iwmmx support for PJ4
>
>On Wed, 17 Nov 2010, Haojian Zhuang wrote:
>
>>
>>
>> >-----Original Message-----
>> >From: Haojian Zhuang [mailto:haojian.zhuang at marvell.com]
>> >Sent: 2010年11月17日 7:04 PM
>> >To: linux-arm-kernel at lists.infradead.org
>> >Cc: Haojian Zhuang; Zhou Zhu; Eric Miao; Nicolas Pitre
>> >Subject: [PATCH 9/9] ARM: pxa: add iwmmx support for PJ4
>> >
>> >iwmmxt is used in XScale, XScale3, Mohawk and PJ4 core. But the instructions
>> >of accessing CP0 and CP1 is changed in PJ4. Append more files to support
>> >iwmmxt in PJ4 core.
>> >
>> >Signed-off-by: Zhou Zhu <zzhu3 at marvell.com>
>> >Signed-off-by: Haojian Zhuang <haojian.zhuang at marvell.com>
>> >Cc: Eric Miao <eric.y.miao at gmail.com>
>> >Cc: Nicolas Pitre <nico at fluxnic.net>
>> >---
>> > arch/arm/Kconfig         |    4 +-
>> > arch/arm/kernel/Makefile |    1 +
>> > arch/arm/kernel/iwmmxt.S |   55 +++++++++++++++++++++++++++++++++++----
>---
>> >----
>> > 3 files changed, 45 insertions(+), 15 deletions(-)
>> >
>>
>> Changelog:
>> 1. Append missing pj4-cp0.c.
>
>OK... some more comments there:
>
>+static int __init pj4_cp0_init(void)
>+{
>+       u32 cp_access;
>+
>+       cp_access = pj4_cp_access_read() & ~0xf;
>+       pj4_cp_access_write(cp_access | 0xf);
>
>You clear all first 4 bits just to set them all again.  Isn't the first
>mask redundant?
>
>+       printk(KERN_INFO "XScale iWMMXt coprocessor detected.\n");
>
>You are not really detecting anything here, and this is not for XScale
>either.  What about ""PJ4 iWMMXt coprocessor enabled.\n" instead?
>
>+       elf_hwcap |= HWCAP_IWMMXT;
>+       thread_register_notifier(&iwmmxt_notifier_block);
>+
>+       pj4_cp_access_write(cp_access);
>
>And here you are clearing access to the coprocessor.  There is nothing
>that required access to it from the moment it was set at the beginning
>of the function, so maybe you should have only cleared it at the
>beginning instead.
>
>
>Nicolas

Thanks for your comments. Now it's fixed in attachment.

Best Regards
Haojian
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