[PATCH v3 00/27] kill devm_ioremap_nocache
xieyisheng1 at huawei.com
Mon Dec 25 01:09:10 UTC 2017
hi Christophe and Greg,
On 2017/12/24 16:55, christophe leroy wrote:
> Le 23/12/2017 à 16:57, Guenter Roeck a écrit :
>> On 12/23/2017 05:48 AM, Greg KH wrote:
>>> On Sat, Dec 23, 2017 at 06:55:25PM +0800, Yisheng Xie wrote:
>>>> Hi all,
>>>> When I tried to use devm_ioremap function and review related code, I found
>>>> devm_ioremap and devm_ioremap_nocache is almost the same with each other,
>>>> except one use ioremap while the other use ioremap_nocache.
>>> For all arches? Really? Look at MIPS, and x86, they have different
>> Both mips and x86 end up mapping the same function, but other arches don't.
>> mn10300 is one where ioremap and ioremap_nocache are definitely different.
> alpha: identical
> arc: identical
> arm: identical
> arm64: identical
> cris: different <==
> frv: identical
> hexagone: identical
> ia64: different <==
> m32r: identical
> m68k: identical
> metag: identical
> microblaze: identical
> mips: identical
> mn10300: different <==
> nios: identical
> openrisc: different <==
> parisc: identical
> riscv: identical
> s390: identical
> sh: identical
> sparc: identical
> tile: identical
> um: rely on asm/generic
> unicore32: identical
> x86: identical
> asm/generic (no mmu): identical
Wow, that's correct, sorry for I have just checked the main archs, I means
x86,arm, arm64, mips.
However, I stall have no idea about why these 4 archs want different ioremap
function with others. Drivers seems cannot aware this? If driver call ioremap
want he really want for there 4 archs, cache or nocache?
> So 4 among all arches seems to have ioremap() and ioremap_nocache() being different.
> Could we have a define set by the 4 arches on which ioremap() and ioremap_nocache() are different, something like HAVE_DIFFERENT_IOREMAP_NOCACHE ?
Then, what the HAVE_DIFFERENT_IOREMAP_NOCACHE is uesed for ?
>>>> While ioremap's
>>>> default function is ioremap_nocache, so devm_ioremap_nocache also have the
>>>> same function with devm_ioremap, which can just be killed to reduce the size
>>>> of devres.o(from 20304 bytes to 18992 bytes in my compile environment).
>>>> I have posted two versions, which use macro instead of function for
>>>> devm_ioremap_nocache or devm_ioremap. And Greg suggest me to kill
>>>> devm_ioremap_nocache for no need to keep a macro around for the duplicate
>>>> thing. So here comes v3 and please help to review.
>>> I don't think this can be done, what am I missing? These functions are
>>> not identical, sorry for missing that before.
Never mind, I should checked all the arches, sorry about that.
>>> greg k-h
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