The current 2.4-devel tree never assigns any memory to the ISA DMA zone,
irrespective of the setting of ISA_DMA_THRESHOLD. As I'm currently
trying to get a floppy working on a platform with 24-bit ISA DMA in its
Southbridge, this looks like a problem.
How do people feel about the attached patch? This should only change
behavior for platforms which set ISA_DMA_THRESHOLD to a value other than
0 or (-1)L.
--
Adrian Cox http://www.humboldt.co.uk/
Hi
Seems like you are facing the same problem as i do. But IIRC i think you
have to adjust the code in include/asm/dma.h (and possibly other places)
as well (at least in 2.4.14, not sure about the later kernels).
BTW:
What south bridge do you use? Some of the newer ones offer 32bit
addressing capability for DMA.
Adrian Cox wrote:
The current 2.4-devel tree never assigns any memory to the ISA DMA zone,
irrespective of the setting of ISA_DMA_THRESHOLD. As I'm currently
trying to get a floppy working on a platform with 24-bit ISA DMA in its
Southbridge, this looks like a problem.
How do people feel about the attached patch? This should only change
behavior for platforms which set ISA_DMA_THRESHOLD to a value other than
0 or (-1)L.
[stuff deleted]
Dave
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
David Müller (ELSOFT AG) wrote:
Seems like you are facing the same problem as i do. But IIRC i think you
have to adjust the code in include/asm/dma.h (and possibly other places)
as well (at least in 2.4.14, not sure about the later kernels).
The main problem I can see is that the code always writes to the
DMA_HI_PAGE_x registers, irrespective of whether they actually exist.
This should be harmless, as nothing else is mapped to those locations.
What south bridge do you use? Some of the newer ones offer 32bit
addressing capability for DMA.
Via686a. As I understand it, 32-bit DMA uses the DMA_HI_PAGE_x registers
from 0x487 to 0x48a, and the Via manual doesn't claim to have any
registers in that range. The only 32-bit DMA southbridge I've
encountered is the Winbond chip on the Sandpoint, and that chip doesn't
have UDMA66, USB, and audio.
--
Adrian Cox http://www.humboldt.co.uk/
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
On Thu, 20 Dec 2001, Adrian Cox wrote:
David Müller (ELSOFT AG) wrote:
quoted
What south bridge do you use? Some of the newer ones offer 32bit
addressing capability for DMA.
Via686a. As I understand it, 32-bit DMA uses the DMA_HI_PAGE_x registers
from 0x487 to 0x48a, and the Via manual doesn't claim to have any
registers in that range. The only 32-bit DMA southbridge I've
encountered is the Winbond chip on the Sandpoint, and that chip doesn't
have UDMA66, USB, and audio.
And the Winbond South Bridge on the LongTrail (most probably the same chip).
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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