On Mon, 27 Aug 2001 18:51:59 +0100, Philip Blundell <firstname.lastname@example.org> wrote:
> >Doesn't that imply, though, that we should dump the software-ECP code?
> >Is that what we want to do?
> No, I don't think so. PARPORT_MODE_ECP is supposed to mean "hardware
> acceleration for ECP is available". There isn't currently a specific
> capability bit to mean "software emulation of ECP is available", though in
> practice PARPORT_MODE_PCSPP probably means about that.
OK, now I'm confused. parport_pc on my machine is correctly setting
the PARPORT_MODE_ECP bit in port->modes because the hardware supports
ECP mode. However, unless I build parport_pc with
CONFIG_PARPORT_PC_FIFO and unless the parport_pc options are set
properly (i.e. unless parport_pc is configured to use DMA) the data
transfers don't work properly -- I get garbage data. I would like
this not to happen, so either I need some fixes to the software-ECP
code (Tim alluded to some changes to this code earlier) or parport_pc
should disallow ECP mode if it's not configured to use DMA. I think
you mean we should do the former, in which case other than the bug
fixes for software-ECP parport_pc doesn't require any changes. Is
that correct? I should still, of course, change lp.c to look at
the mode bits before attempting to use ECP mode.
-- Dave Strauss
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This archive was generated by hypermail 2b29 : Mon Aug 27 2001 - 14:18:09 EDT