What kind of situation trigger the alloc_surface & free_surface function in video.c (video-driver)

[Alex Deucher]

On Wed, Aug 11, 2010 at 11:06 PM, Cui, Hunk <Hunk.Cui at amd.com> wrote:
> Hi, Alex,
>        Many thanks for your hints, about the xawtv, only know it is a television viewer-X11 application, I will try to it, any other info, I will reform to you. :)

I think it might have only used it in conjunction with the old v4l
ddx.  I wouldn't worry too much about it.

Alex

>
> Thanks,
> Hunk Cui
>
>> -----Original Message-----
>> From: Alex Deucher [mailto:alexdeucher at gmail.com]
>> Sent: Thursday, August 12, 2010 12:29 AM
>> To: Adam Jackson
>> Cc: Cui, Hunk; xorg-driver-geode at lists.x.org; xorg-devel at lists.x.org
>> Subject: Re: What kind of situation trigger the alloc_surface & free_surface
>> function in video.c (video-driver)
>>
>> On Wed, Aug 11, 2010 at 10:26 AM, Adam Jackson <ajax at nwnk.net> wrote:
>> > On Wed, 2010-08-11 at 10:24 +0800, Cui, Hunk wrote:
>> >> Hi, guys,
>> >>       Now I am researching about allocate the video overlay memory,
>> >> some confuse to inquire.
>> >>       In xf86-video-geode -> lx_video.c -> LXInitOffscreenImages:
>> >>               alloc_surface = LXAllocateSurface;
>> >>               free_surface  = LXFreeSurface;
>> >>
>> >>       In xf86-video-ati         -> radeon_video.c ->
>> >> RADEONInitOffscreenImages:
>> >>               alloc_surface = RADEONAllocateSurface;
>> >>               free_surface  = RADEONFreeSurface;
>> >>
>> >>       Inquire: what kind of situation trigger above functions? What
>> >> are the mainly effect?
>> >
>> > The answer appears to be: nothing.  The alloc_surface hook is never
>> > called from the core X server.  Which does sort of make me wonder what
>> > people thought they were writing when they wrote them...
>> >
>> > I suspect the intent was to allow XV to offscreen surfaces.
>>
>> IIRC, these used to be used by the v4l ddx to stream directly to
>> another Xv adapter, or something like that.  I think xawtv used to use
>> it back in the day.
>>
>> Alex
>
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