Re: [Gumstix-users] USB Host

[Pascal A. B. <pas...@wa...>]

Doug Sutherland writes:
 > Since connex doesn't have the DMA signals, I think I will proceed
 > working with SL81HS while keeping ISP1761 and a strategic goal.

The ISP1761 datasheet says it supports even good old PIO, so are
you sure DREQ/DACK are mandatory to connect it with the gumstix ?
See "The system DMA controller may also start a transfer without
the need of DREQ, if the memory is available for the data transfer
and the ISP1761 DMA programming is completed" on page 21.

Or are you concerned about performance ?  The on-chip buffer is
60 kB, i.e. 1 ms worth of traffic at 480 Mbit/s. I don't know whether
you could reach that speed, but it looks like interrupt-driven,
CPU-controlled DMA would work as usual.

Note that the complaints about the lack of DMA signals in the last
few weeks were about connecting cheap synchronous peripherals which
don't have a FIFO and which are not even really designed for DMA.

-- Pascal