On Mon, 13 Mar 2006 05:19:41 -0800 (PST), John Carlson <[EMAIL PROTECTED]>
wrote:
> [...] It generally comes down to internal priority
> issues in the printer. The internal usb controller
> has a higher then some time critical process and will
> cause that process to timeout if data is sent/received
> at a high data rate. When that process times out, the
> printer basically hangs for printing purposes. To
> work around these problems it becomes necessary to
> throttle the sending/receiving of data. It would be
> nice if the company I work for would provide this
> information so that we could handle these problem
> printers without having to experiment with data rates.
Right. Printer firmware essentially has to support hard
real time, because of the head movements.
I think that in our case, Jan should start with something like this:
--- foo2zjs/foo2zjs.c 2005-12-23 15:37:41.000000000 -0800
+++ foo2zjs-4rychter/foo2zjs.c 2006-03-13 10:38:45.000000000 -0800
@@ -310,12 +310,14 @@ chunk_write_rsvd(unsigned long type, uns
{
ZJ_HEADER chunk;
+ usleep(10*1000);
chunk.type = be32(type);
chunk.items = be32(items);
chunk.size = be32(sizeof(ZJ_HEADER) + size);
chunk.reserved = be16(rsvd);
chunk.signature = 0x5a5a;
fwrite(&chunk, 1, sizeof(ZJ_HEADER), fp);
+ fflush(fp);
}
static void
Don't forget that you have to run "foo2zjs > /dev/usb/lp0" for
the above to have any effect.
If the patch works, we can think about adding necessary autodetection
with fileno() and ioctl() - no need to slow down printing into
a data stream. If it does not, well, it can be something else.
Jan, would you mind hashing this out with Rick? I think it's out
of the kernel area.
-- Pete
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