1100 DMA channels

Hasjim Williams jornada820@lists.futaris.org
Sat Feb 14 02:45:00 CET 2004


The LCD uses two separate DMA channels (using DBAR1/DBAR2) - 1 for the
upper panel and one for the bottom. 

The VGA output sets its DMA mode in bit 12 of VideoControl. VgaDBAR and
VgaDCAR are the equivalent of the LCD DBAR1, DCAR1, DBAR2 and DCAR2.  The
VGA output really depends on what mode its being used in.  I assume it's
possible to both unified display mode and dedicated display mode on the
Jornada 820, as both are supported in Windows CE.  One thing that I did
notice about unified display mode (using "HP Show"), is that the palette
would not be updated automatically if you write to the palette registers
directly.  The dedicated display mode will support whatever resolution
that fits in the framebuffer.

The VGA controller can use the Shared Memory Controller and be a Bus
Master, and the USB interface can only be a Bus Master.  I'm not sure if
it's possible to use DMA for the USB host controller.  The USB interface
gets everything from the AMBA system bus (ASB).  The AMBA peripheral bus
(APB) sets up the slaves, etc.

If you think PCMCIA/CF is trashing DDAR2, try removing the PCMCIA support
from the kernel and recompiling...  I assume your register monitoring
driver are/will be in the ramdisk?  


On Thu, 12 Feb 2004 18:41:24 +0100, "Oleg Gusev"
<oleg@usm.uni-muenchen.de> said:
>  wince configures six DMA channels this way:
>  0,1 -> IRDA rx/tx,
>  2,3 -> MCP audio rx/tx,
>  4,5 -> Ser3(serial port) rx/tx
>  USB and VGA use busmaster access to RAM.
>  For some reason the DDAR2 is trashed in linux.
>  This can be some side effect of PCMCIA/CF 
>  setup/operation...
>  Oleg.

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