The latest CPiA webcam patches contain a DMA read function.
Unfortunately, you will have to do a little (very little) bit of kernel
hacking to get it working with anything other than CPiA. It might be
worth looking at.
Quoted from mark anderson on Mon, Mar 10, 2003 at 05:49:56PM -0700.
> I'm playing with some home brewed hardware to upload data into
> my linux box. With EPP I'm getting about .5 MBytes/sec. I see
> claims that 2M should be the upper limit. Is there a specific
> mode that runs this fast (EPP/ECP/???). I can make my hardware
> do whatever protocol and timing makes things fastest.
>
> In a related speed issue, I'd like to use the DMA channel. However,
> I've found a note in the parport bug list (Suse, 2.4.10-4.GB):
>
> o parport_pc_ecp_read_block_pio() is broken. parport will revert to the
> software-driven mode in ieee1284_ops.c
>
> Is this telling me that DMA reads under ECP are broken? As I read
> various parallel port documents I'm lead to believe that only ECP
> supports DMA.
>
> Any thoughts would be appreciated. Thanks.
>
> --mark
>
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