Is there the possibility to support EXA for legacy S3 chips?

[Alex Deucher]

On Thu, Jun 4, 2009 at 11:54 AM, Evgeny M. Zubok <evgeny.zubok at tochka.ru> wrote:
> Michel Dänzer <michel at daenzer.net> writes:
>
>>> EXA bug: Calling FinishAccess on pixmap 0x9278d68 with index 1 while
>>> it should have been (nil).
>>
>> This may indeed be a bug, Maarten? Might be interesting to see gdb
>> backtraces for when these trigger.
>
> Is the https://bugs.freedesktop.org/show_bug.cgi?id=20212 relevant?
>
>
>>> However the main problem with this method is that memory manager
>>> doesn't effectively use the offscreen in this case.
>>
>> Indeed, I'm afraid EXA just doesn't offer any advantages over XAA for
>> such limited hardware.
>
> I have the same thoughts now. In addition I discovered that S3 couldn't
> copy pixmaps with different colour depth from offscreen. For example,
> when using 16 bpp framebuffer. Some source pixmaps have 16 bpp, and
> others have 32 bpp. This results to incorrect 32 bpp pixmaps copying
> into frambuffer. So on S3 the EXA works fine only with 32 bpp fb but not
> with 16 bpp fb. Other hardware with EXA support have not any problems
> with different pixmap depths because their depth may be specified for
> graphic processor. Also my tests showed that drawing speed with EXA on
> very slow PC was the same as with shadow framebuffer (and less than
> XAA). Currently I think that EXA support does not make sense for the
> S3. Only the boards with 4/8 Mb video RAM may be the exception and only
> for depth 24 / 32 bpp fb.

EXA copy shouldn't ask for blits across color depths (need composite
for that), however, it does store buffers of different color depths in
offscreen memory, so you'd need to be to adjust the depth of the
blitter on the fly.

Alex