From: catalin.marinas@arm.com (Catalin Marinas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCHv4 3/5] common: dma-mapping: Introduce common remapping functions
Date: Thu, 24 Jul 2014 14:52:38 +0100 [thread overview]
Message-ID: <20140724135238.GC13371@arm.com> (raw)
In-Reply-To: <53D02F7B.5020309@codeaurora.org>
On Wed, Jul 23, 2014 at 10:56:11PM +0100, Laura Abbott wrote:
> On 7/23/2014 3:45 AM, Catalin Marinas wrote:
> > On Wed, Jul 23, 2014 at 02:35:06AM +0100, Laura Abbott wrote:
> >> --- a/drivers/base/dma-mapping.c
> >> +++ b/drivers/base/dma-mapping.c
> > [...]
> >> +void *dma_common_contiguous_remap(struct page *page, size_t size,
> >> + unsigned long vm_flags,
> >> + pgprot_t prot, const void *caller)
> >> +{
> >> + int i;
> >> + struct page **pages;
> >> + void *ptr;
> >> +
> >> + pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
> >> + if (!pages)
> >> + return NULL;
> >> +
> >> + for (i = 0; i < (size >> PAGE_SHIFT); i++)
> >> + pages[i] = page + i;
> >> +
> >> + ptr = dma_common_pages_remap(pages, size, vm_flags, prot, caller);
> >> +
> >> + kfree(pages);
> >> +
> >> + return ptr;
> >> +}
> >
> > You could avoid the dma_common_page_remap() here (and kmalloc) and
> > simply use ioremap_page_range(). We know that
> > dma_common_contiguous_remap() is only called with contiguous physical
> > range, so ioremap_page_range() is suitable. It also makes it a
> > non-functional change for arch/arm.
>
> My original thought with using map_vm_area vs. ioremap_page_range was
> that ioremap_page_range is really intended for mapping io devices and
> the like into the kernel virtual address space. map_vm_area is designed
> to handle pages of kernel managed memory. Perhaps it's too nit-picky
> a distinction though.
I think you are right. We had a discussion in the past about using
ioremap on valid RAM addresses and decided not to allow this. This would
be similar with the ioremap_page_range() here.
>From my perspective, you can leave the code as is (wouldn't be any
functional change for arm64 since it was using vmap() already). But
please add a comment in the commit log about this change.
--
Catalin
next prev parent reply other threads:[~2014-07-24 13:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-23 1:35 [PATCHv4 0/5] Atomic pool for arm64 Laura Abbott
2014-07-23 1:35 ` [PATCHv4 1/5] lib/genalloc.c: Add power aligned algorithm Laura Abbott
2014-07-23 1:35 ` [PATCHv4 2/5] lib/genalloc.c: Add genpool range check function Laura Abbott
2014-07-23 1:35 ` [PATCHv4 3/5] common: dma-mapping: Introduce common remapping functions Laura Abbott
2014-07-23 10:45 ` Catalin Marinas
2014-07-23 21:56 ` Laura Abbott
2014-07-24 13:52 ` Catalin Marinas [this message]
2014-07-23 11:16 ` Catalin Marinas
2014-07-23 1:35 ` [PATCHv4 4/5] arm: use genalloc for the atomic pool Laura Abbott
2014-07-23 1:35 ` [PATCHv4 5/5] arm64: Add atomic pool for non-coherent and CMA allocations Laura Abbott
2014-07-24 13:56 ` [PATCHv4 0/5] Atomic pool for arm64 Catalin Marinas
-- strict thread matches above, loose matches on Subject: below --
2014-07-02 18:03 [PATCHv4 0/5] DMA " Laura Abbott
2014-07-02 18:03 ` [PATCHv4 3/5] common: dma-mapping: Introduce common remapping functions Laura Abbott
2014-07-09 22:46 ` Olof Johansson
2014-07-18 14:13 ` Catalin Marinas
2014-07-18 13:53 ` Catalin Marinas
2014-07-21 19:33 ` Laura Abbott
2014-07-22 16:04 ` Catalin Marinas
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