[PATCH] drm/gma500: remove the process of stolen page in page fault handler.

[jiang.biao2 at zte.com.cn]

Patrik Jakobsson <patrik.r.jakobsson at gmail.com> wrote 2016/09/02 21:54:41:

> Patrik Jakobsson <patrik.r.jakobsson at gmail.com> 
> 2016/09/02 21:54
> 
> Re: [PATCH] drm/gma500: remove the process of stolen page in page 
> fault handler.
> 
> On Fri, Sep 2, 2016 at 11:31 AM,  <jiang.biao2 at zte.com.cn> wrote:
> >
> > JiangBiao162664/user/zte_ltd Wrote 2016/08/31 10:27:34:
> >
> >> JiangBiao162664/user/zte_ltd
> >> 2016/08/31 10:27
> >>
> >> From
> >> Patrik Jakobsson <patrik.r.jakobsson at gmail.com>,
> >> Re: [PATCH] drm/gma500: remove the process of stolen page in page
> >> fault handler.
> >>
> >> Patrik Jakobsson <patrik.r.jakobsson at gmail.com> wrote on 2016/08/30
> >> 18:21:08:
> >>
> >> > Patrik Jakobsson <patrik.r.jakobsson at gmail.com>
> >> > 2016/08/30 18:21
> >> >
> >> > From
> >> > jiang.biao2 at zte.com.cn,
> >> > cc
> >> > dri-devel <dri-devel at lists.freedesktop.org>
> >> > Re: [PATCH] drm/gma500: remove the process of stolen page in page
> >> fault handler.
> >> >
> >> > On Tue, Aug 30, 2016 at 7:10 AM,  <jiang.biao2 at zte.com.cn> wrote:
> >> > >
> >> > > Direct gtt range is used in the page fault scene in current 
driver,
> >> > > instead of stolen page. So no need to keep relative process.
> >> >
> >> > Hi
> >> >
> >> > Are you saying that we don't use stolen memory? Afaik stolen memory
> >> > should be accessed through the stolen range so we do need this.
> >> >
> >> > -Patrik
> >> >
> >> As far as I can see, the stolen memory is only used by fbdev driver
> >> in gma500,
> >> but the fbdev driver maps the stloen memory directly in 
psbfb_vm_fault,
> >> not
> >> using psb_gem_fault to map the stolen memory.
> >> The only scenario using the psb_gem_fault is the gtt range created by
> >> psb_gem_create, which alloc the gtt range without stolen memory 
backed.
> >
> >> If I missed something, pls enlighten me.
> >> Thanks a lot.
> >
> > Hi Patrik,
> >
> > Could you please help to confirm my question?
> > Thank you very much.
> 
> Hi,
> 
> The assumption that stolen memory will never be used with
> psb_gem_create() might not hold true in the future and silently
> breaking support for it ito save a few lines of code is not the right
> way to do it. Actually, if we find use for stolen memory we would
> basically get memory for free since it is already reserved for
> graphics usage.
> 
> Cheers
> Patrik

Understood, but maybe It's better to add it when it's actually used.
Indeed, that does not that matter.

Thanks for the reply.
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