[Libdlo] Synchronous vs. asynchronous USB

[Steve (Endurance)]

On 25 May, Phil Endecott <spam_from_libdlo at chezphil.org> wrote:
> I'm not sure what libdlo should do about this.  Perhaps a useful first 
> step is to make it possible for users to get at the format conversion 
> stuff separately from the USB transport.  I.e. (pseudo-code) 
> re-implement things like dlo_copy_host_bmp as follows:
>
> dlo_copy_host_bmp(...) {
>    buffer buf;
>    dlo_make_copy_host_bmp_cmds(....,buf);
>    usb_bulk_write(buf);
> }

Interesting suggestion. Reason libdlo is currently structured in this way
because of its original use in embedded systems, where memory for large
buffers is at a premium. It was also specified to be single threaded.

Your suggestion is certainly possible, we'd want to wrap the
usb_bulk_write() into a dlo_ call which is published in libdlo.h so that
it's consistent with the rest of the API. 

> Basically it's WiFi + MIPS processor running Linux + 32 MBytes RAM + 1 
> USB 2.0 host controller. Plug this in to your DisplayLink device and 
> you have a wireless display.

We've run a version of libdlo on an ASUS WL-500gp router running OpenWrt in
the past. That was also a Broadcom (MIPS) CPU, 32MiB RAM, 8MiB flash and USB
2.0. It worked pretty well - we could certainly run a slideshow application
which was driving four DisplayLink devices from it.

Thanks,

Steve

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Stephen Revill, Technical Project Leader           Tel: +44 (0) 1353 740 267
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