Re: [PATCH 0/2] Experimental Amiga Zorro ESP driver

Tuomas Vainikka
2013-08-19T11:47:17Z

On 08/19/2013 11:48 AM, Michael Schmitz wrote:
> Geert,
>> On Sun, Aug 18, 2013 at 10:58 AM, Michael Schmitz
>> <schmitzmic@gmail.com> wrote:
>>> I'll also need to check the command_block and command_block_dma
>>> addresses -
>>> does the DMA require virtual or physical addresses?
>>
>> Physical, of course.
>
> :-) VDMA was invented a bit later ...
>
>
> I'll go check the usage of the DMA API calls again, but as the driver
> seems to do DMA fine until the short transfer, that seems the most
> likely cause. PIO for dma_count < 7 might be an option.
>
> I see transfers with esp_count=1 and dma_count=7 in the log - wonder
> why that works but the short 2/2 byte case does not.
>
Is it possible that the problem is with memory alignment?

http://fxr.watson.org/fxr/source/arch/amiga/dev/bzivsc.c?v=NETBSD#L360
https://groups.google.com/d/msg/comp.sys.amiga.hardware/FXwaSFoAPxc/zsXeP7PB6RoJ

-Tuomas