Kurt Roeckx <[EMAIL PROTECTED]> wrote: Hi,
> I had a problem in my program where it did > ieee1284_negotiate(M1284_NIBBLE) but I didn't check the return > value, and then just called ieee1284_nibble_read(). > ieee1284_nibble_read() returns -1 (as expected), I think errno is > set to EAGAIN. But the problem is that the next time I do > ieee1284_negotiate() and it is succesful, ieee1284_nibble_read() > still returns -1. > > It seems that when calling ieee1284_nibble_read() (using ppdev) it > always does: > set_mode (port, M1284_NIBBLE, 0, 0); > > I think the problem is doing the ioctl(PPSETMODE) and that it shouldn't > be doing that until the negotiation was succesful. I'm not sure, but this may have to do with this remark from the ieee1284_negotiate() manpage: An IEEE 1284-compliant device will require a successful negotiation to a particular mode before it is used for data transfer (but simpler devices may not if they only speak one transfer mode). > You could argue that this isn't exactly a bug in libieee1284, > but it would be nice that it didn't set the mode until it > was properly negotiated. I'd argue that you shouldn't call an I/O method if you haven't properly negotiated the transfer mode first, indeed :) The code could check port->current_mode to make sure the negotiation indeed took place and ended successfully, but then I'm not sure it's a good idea. I imagine that could become a problem with some devices, given that "standard compliance" in this area is at best a very abstract concept... Anyway, Tim will know way better than I do ;) JB. -- Julien BLACHE - Debian & GNU/Linux Developer - <[EMAIL PROTECTED]> Public key available on <http://www.jblache.org> - KeyID: F5D6 5169 GPG Fingerprint : 935A 79F1 C8B3 3521 FD62 7CC7 CD61 4FD7 F5D6 5169 -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
