lkml.org 
[lkml]   [2013]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] ARM: mm: clean-up in order to reduce to call kmap_high_get()
On Mon, Mar 04, 2013 at 01:50:09PM +0900, Joonsoo Kim wrote:
> In kmap_atomic(), kmap_high_get() is invoked for checking already
> mapped area. In __flush_dcache_page() and dma_cache_maint_page(),
> we explicitly call kmap_high_get() before kmap_atomic()
> when cache_is_vipt(), so kmap_high_get() can be invoked twice.
> This is useless operation, so remove one.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index c7e3759..b7711be 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -822,16 +822,16 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset,
> if (PageHighMem(page)) {
> if (len + offset > PAGE_SIZE)
> len = PAGE_SIZE - offset;
> - vaddr = kmap_high_get(page);
> - if (vaddr) {
> - vaddr += offset;
> - op(vaddr, len, dir);
> - kunmap_high(page);
> - } else if (cache_is_vipt()) {
> - /* unmapped pages might still be cached */
> + if (cache_is_vipt()) {

This should be:
if (cache_is_vipt_nonaliasing())

to make it _explicit_ that this technique is only for non-aliasing VIPT
caches (this doesn't work on any other of our cache types.) Yes, I
know we don't support highmem with VIPT aliasing caches - but still,
we should ensure that this is self-documented in this code.

Same for arch/arm/mm/flush.c


\
 
 \ /
  Last update: 2013-03-07 16:21    [W:0.059 / U:0.888 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site