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 functions.
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 ?
Thanks Yisheng
Christophe
Guenter
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[1] or devm_ioremap[2]. 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.
thanks,
greg k-h
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