Re: [PARPORT] ppdev ECP addr ops

Tim Waugh (
Tue, 27 Jul 1999 16:17:04 +0100 (GMT)

On Mon, 26 Jul 1999, Thomas Sailer wrote:

> Now, my tests with 2.3.11 (with the ppdev patch from pre-2.3.12-5
> applied) gave the following results:
> - software emul EPP: the program hanged forever or until a PTRACE
> attach,
> in which case it immediately returned (having no bytes transmitted).

I can't see how that can happen. Can you put strategic printks in to find
out the execution path? Or at least, what does ps say that the process's
WCHAN is? Also, were you reading or writing, or both?

> - hardware ECP: ecp_write_addr works, ecp_read_data returned
> immediately, having
> no bytes read
> - software ECP: same as hw ECP

The 'hardware ECP' function might just call through to the 'software ECP'
function. How many bytes were you trying to read, and how exactly were
you doing it?

As for parport_ieee1284_ecp_read_data returning 0 immediately, I don't see
how that can happen except if the timeout for that port is zero.


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This archive was generated by hypermail 2.0b3 on Tue 27 Jul 1999 - 11:41:40 EDT