On Thu, Mar 6, 2008 at 2:58 PM, Michael Lorenz <macallan@xxxxxxxxxx> wrote:
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>
> Hello,
>
> On Mar 6, 2008, at 14:12, Alex Deucher wrote:
>
> > On Thu, Mar 6, 2008 at 2:00 PM, Michael Lorenz
> > <macallan@xxxxxxxxxx> wrote:
> >> -----BEGIN PGP SIGNED MESSAGE-----
> >> Hash: SHA1
> >>
> >> Hello,
> >>
> >> On Mar 5, 2008, at 19:06, Alex Deucher wrote:
> >>
> >>> On Tue, Mar 4, 2008 at 5:34 PM, Michael Lorenz
> >>> <macallan@xxxxxxxxxx> wrote:
> >>>> -----BEGIN PGP SIGNED MESSAGE-----
> >>>> Hash: SHA1
> >>>>
> >>>> Hello,
> >>>>
> >>>>
> >>>> On Mar 4, 2008, at 15:37, Marc Aurele La France wrote:
> >>>>
> >>>>> On Mon, 3 Mar 2008, Michael Lorenz wrote:
> >>>>>
> >>>>>> I noticed the following - XAACopyArea() only attempts to use
> >>>>>> accelerated WriteImage() when writing to a DRAWABLE_WINDOW but
> >>>>>> not
> >>>>>> on off-screen pixmaps. I used the following changes to make it
> >>>>>> work:
> >>>>>
> >>>>>> diff -u -w -r1.1.1.3 xaaCpyArea.c
> >>>>>> - --- xaaCpyArea.c 9 Jun 2001 15:09:02 -0000 1.1.1.3
> >>>>>> +++ xaaCpyArea.c 3 Mar 2008 20:51:05 -0000
> >>>>>> @@ -64,9 +64,16 @@
> >>>>>> return (XAABitBlt( pSrcDrawable, pDstDrawable,
> >>>>>> pGC, srcx, srcy, width, height, dstx, dsty,
> >>>>>> XAADoBitBlt, 0L));
> >>>>>> + } else {
> >>>>>> + if(infoRec->ScreenToScreenBitBlt &&
> >>>>>> + CHECK_ROP(pGC,infoRec->ScreenToScreenBitBltFlags) &&
> >>>>>> + CHECK_ROPSRC(pGC,infoRec->ScreenToScreenBitBltFlags) &&
> >>>>>> + CHECK_PLANEMASK(pGC,infoRec-
> >>>>>> >ScreenToScreenBitBltFlags))
> >>>>>> + return (XAABitBlt( pSrcDrawable, pDstDrawable,
> >>>>>> + pGC, srcx, srcy, width, height, dstx, dsty,
> >>>>>> + XAADoImageWrite, 0L));
> >>>>>> }
> >>>>>> }
> >>>>>
> >>>>> This does not look correct. Shouldn't this be more in line with
> >>>>> the case where the destination drawable is a window? (i.e. test
> >>>>> bitsPerPixel's and WritePixmap files instead of
> >>>>> ScreenToScreenBitBlt).
> >>>>
> >>>> The whole logic looks a little bit fishy, I used the first if()'s
> >>>> source-in-memory branch first but wasn't quite sure if that's
> >>>> doing
> >>>> the right thing, where it;s now looked better to me but I won't
> >>>> claim
> >>>> I completely understand XAA's inner voodoo. All I want is the make
> >>>> XAA use ImageWrite()s for all RAM-to-VRAM transfers if the driver
> >>>> supports it.
> >>>> Otherwise, teaching the framebuffer layer to cope with a tiled
> >>>> framebuffer might be necessary in the long run, any pointers
> >>>> where to
> >>>> start?
> >>>
> >>> Several drivers (radeon, intel, savage) in the Xorg tree provide
> >>> support for various tiling methods. Generally the chip provides a
> >>> surface control or aperture for exposing a tiled region to the
> >>> CPU as
> >>> a linear surface. For acceleration, you have to keep track of what
> >>> buffers are tiled in the driver and do the right thing with the
> >>> blitter when using those surfaces.
> >>
> >> Yeah, I'm dimly aware of these things - my problem is that the
> >> hardware in question doesn't give me a linear view on the
> >> framebuffer.
> >> All I have is a small linear buffer I can use to DMA data in or out
> >> of the tiled framebuffer. The other problem is that the machine's
> >> native pixel format is RGBA, if I want 24bit colour that's the only
> >> one I can use. Fortunately the DMA engine can convert pixels on the
> >> fly so I can pretend it's ABGR. So pixels would have to be endian-
> >> flipped as well when the fb layer accesses VRAM - is there any prior
> >> art for that?
> >
> > EXA has prepare/finish access hooks for CPU access to buffers. I
> > don't think XAA has anything similar. There's also an wrapable FB
> > module, although I think it's only available in Xorg.
>
> I'll have a look at that - the main reason I'm using XFree86 is that
> it's already working on NetBSD/sgimips, Xorg needs some more work but
> I'll eventually do it.
> Hmm, some drivers access video memory through tiny apertures like the
> VGA range - maybe I can do something like this - let the rest of the
> Xserver render into my DMA buffer and then blit it in place.
Use shadowfb and hook in a custom shadowupdate() function.
Alex
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