- From: Tomasz Motylewski <motyl_at_stan.chemie.unibas.ch>
- Date: Sun, 20 Oct 2002 10:41:56 +0200 (CEST)
On Sat, 19 Oct 2002, David Schleef wrote: > Continuous DMA works fine. However, it won't work with your hack. > > The best way to do it is to run the command, then access the buffer > pointer using comedi_mmap() and the read buffer offsets using > comedi_get_buf_head_pos() and comedi_set_user_int_count(). OK, but even if I do not use the hack with substituting my buffers and use comedi_mmap() and then I do not call comedi_get_buf_head_pos() and comedi_set_user_int_count() for the time longer than the length of the buffer, it will overflow? Why I can not just set up the transfer and then peek into the buffer from time to time when(if) I wish? When the DMA ring is circular there is no need for any interrupts at all. I know you will say "register the callback and just do there comedi_set_user_int_count()", but these are precious microseconds! Why Comedi driver can not just configure and start the card and get out of my way? Best regards, -- Tomek P.S. How did you like my linux 2.2 patch?
Received on 2002-10-20Z07:41:56