From mboxrd@z Thu Jan 1 00:00:00 1970 Message-Id: <4.2.2.20000525110602.00a704c0@mail.kerbango.com> Date: Thu, 25 May 2000 11:07:30 -0700 To: gjohnson@research.canon.com.au (Greg Johnson) From: Steve Calfee Subject: Re: IDMA: Setting Up Parameter RAM. Cc: linuxppc-embedded@lists.linuxppc.org In-Reply-To: <20000525060239.3F99C3C989@elph.research.canon.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: At 04:02 PM 5/25/00 +1000, you wrote: >Hi all, > >I am having a little problem with IDMA parameter RAM on the 855T/860. >The problem is that when I set up the parameter RAM's DMA Channel >Mode Register, and the IDMA BD Base Address pointer, the CPM does not >appear to recognise these new values. I am quite confident that I >am setting up the ports etc for our board correctly. I shall elaborate. > >When I power on our board, boot, load our driver for the hardware, >setup the IDMA/Parameter RAM/Buffer Descriptors and attempt to start >an IDMA transfer, nothing happens. (reloading driver and retries >do not work) > >When I then hit the reset button (no power cycle) and go through the >same ritual, IDMA works fine. > >The reason being is that values for the IDMA Parameter RAM DMA Channel >mode register (DCMR) and IDMA BD Base Address pointer (IBASE) that >were written in the first attempt on power-on are preserved in >DPRAM over the reboot. Why would these value apparently be written >in the first attempt, but appear not to be recognised by the CPM??? > >In addition, if I power on, and use the boot loader to program the >IDMA Parameter RAM DCMR and IBASE elements, then boot Linux, load >the driver and attempt a DMA operation, It all works fine. The >reason I don't want to be content with setting this information up >in the boot loader is that we want to be able to eventually allocate >and release buffer descriptors. > >I suspect that I am not setting up something correctly that affects >the way that the Communications Processor responds to changes in the >Parameter RAM. > >Can anyoue offer any clues/hints/guesses??? Check to make sure the addresses you feed the cpm are physical (not memory mapped) addresses. Regards, Steve __________________________________________ Steve Calfee -- embedded systems consultant calfee@home.com cell phone: (510) 468-5837 Kerbango phone: (408) 517-3355 ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/