Re: [PATCH] video: arch specific page protection support for deferred io

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 25 Jun 2009 15:06:24 +0900 Magnus Damm <magnus.damm@gmail.com> wrote:

> On Thu, Jun 25, 2009 at 11:56 AM, Andrew
> Morton<akpm@linux-foundation.org> wrote:
> > On Wed, 24 Jun 2009 19:54:13 +0900 Magnus Damm <magnus.damm@gmail.com> wrote:
> >
> >> From: Magnus Damm <damm@igel.co.jp>
> >>
> >> This patch adds arch specific page protection support to deferred io.
> >>
> >> Instead of overwriting the info->fbops->mmap pointer with the
> >> deferred io specific mmap callback, modify fb_mmap() to include
> >> a #ifdef wrapped call to fb_deferred_io_mmap(). __The function
> >> fb_deferred_io_mmap() is extended to call fb_pgprotect() in the
> >> case of non-vmalloc() frame buffers.
> >>
> >> With this patch uncached deferred io can be used together with
> >> the sh_mobile_lcdcfb driver. Without this patch arch specific
> >> page protection code in fb_pgprotect() never gets invoked with
> >> deferred io.
> >>
> >> Signed-off-by: Magnus Damm <damm@igel.co.jp>
> >> ---
> >>
> >> __For proper runtime operation with uncached vmas make sure
> >> __"[PATCH][RFC] mm: uncached vma support with writenotify"
> >> __is applied. There are no merge order dependencies.
> >
> > So this is dependent upon a patch which is in your tree, which is in
> > linux-next?
> 
> I tried to say that there were _no_ dependencies merge wise. =)
>
> There are 3 levels of dependencies:
> 1: pgprot_noncached() patches from Arnd
> 2: mm: uncached vma support with writenotify
> 3: video: arch specfic page protection support for deferred io
> 
> 2 depends on 1 to compile, but 3 (this one) is disconnected from 2 and
> 1. So this patch can be merged independently.

OIC.  I didn't like the idea of improper runtime operation ;)

Still, it's messy.  If only because various trees might be running
untested combinations of patches.  Can we get these all into the same
tree?  Paul's?

> 
> The code is fbmem.c is currently filled with #ifdefs today, want me
> create inline versions for fb_deferred_io_open() and
> fb_deferred_io_fsync() as well?

It was a minor point.  Your call.

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