[PATCH] Add support for RENDER BGRA formats.

[Mark Kettenis]

> From: Adam Jackson <ajax at nwnk.net>
> Date: Wed, 28 Oct 2009 10:39:29 -0400
> 
> > (--) PCI: (0:0:3:0) 105d:2339:105d:000b Number 9 Imagine-128 II rev 2,
> > Mem @ 0x02000000/8388608, 0x02800000/8388608, 0x03000000/8388608,
> > 0x03800000/8388608, 0x00160000/65536, I/O @ 0x00000600/256, BIOS @
> > 0x????????/32768
> 
> BARs 0 and 1 are memory windows 0 and 1.  We map MW0 for the
> framebuffer, but they're both just views onto the device's VRAM iirc, so
> you should be able to map either one.
> 
> > (--) I128(0): Memory Windows Registers
> > (--) I128(0):   MW0_CTRL 0x00000100
> > (--) I128(0):     AMV 0  MP 0  AMD 0  SEN 0  BSY 1  MDM 0  DEN 0  PSZ 0
> 
> Hm.  Bits 18 through 16 (mask 0x00070000) define the host data format
> for the memory window.  If set, bit 16 swaps bits within each byte
> (whatever that means); bit 17 swaps bytes within each word; and bit 18
> swaps words within each dword.

Excellent!  After initializing MW0_CTRL to 0x00060000, it seems things
just work.  I'll prepare a proper diff to do that on big-endian machines.

To make the card work properly I still have to solve two issues:

1. It seems the ACNTRL register doesn't exist on the i128v2 chip.
   Writes to this register result in a PCI bus error.  This was
   probably never noticed, since on standard PC hardware writes to
   non-existent registers silently fail.  Do the docs contain some
   hints suggesting this is indeed the case?

2. Does the hardware by any chance map the VGA legacy I/O ports within
   one of its BARs?

Thanks,

Mark