[linux-fbdev] Matrox and XFree86 4.0.2 update

[Kostas Gewrgiou]

On Thu, 25 Jan 2001, Geert Uytterhoeven wrote:

> On Thu, 25 Jan 2001, Kostas Gewrgiou wrote:
> > On Wed, 24 Jan 2001, Petr Vandrovec wrote:
> >
> > Nope it won't cause any problems, none of the XF[86][68]_FBDev servers where
> > accelerated for matrox, other libs (SDL etc) that have accel for matroxfb
> > don't work correctly for ppc either.
>
> XF68_FBDev is accelerated for matroxfb, at least on the PPC platform.

Ops i forgot about it, it will be easy to change it though, although
backwards compatibility will be a nightmare :(

> > Changing the endian to little is the *right* thing, big-endian mode doesn't
> > offer us anything beyond problems in matroxfb 8/16 bit accesses become a
> > nightmare there...
>
> 8/16 bit accesses? I assume you're talking about the frame buffer, not about
> the register accesses?

No i am talking about register accesses, for example
the mga driver in xfree86 uses
 #define MGAISBUSY() (INREG8(MGAREG_Status + 2) & 0x01)
SDL uses
 #define mga_wait(space)  {                                             \
        while ( mga_in8(MGAREG_FIFOSTATUS) < space );                   \
 }

Both will fail under big-endian mode in PPC, the addressing is changed
so you have to use something like *(addr + (3-addr%4) to get the right
byte (i hope i got it right, its still early here)

> Currently XF68_FBDev needs a big-endian frame buffer on big-endian machines.

And i don't expect it to change ;P

 Kostas


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