From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 25 Jun 2003 10:24:45 -0400 From: Callebaut Benoit To: Allen Curtis Cc: linuxppc-embedded mailing list Subject: RE: PCI DMA support on the MPC8250 Message-ID: <3EFAF5FC@mailandnews.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: >===== Original Message From Allen Curtis ===== >>But the DMA transfers are working and are 5 time faster. You must only program >>them. It is just 5 registers to configure. You buffers in RAM must be >>allocated with consistent_alloc to avoid caching on them and you must always >>write physical addresses in the DMA registers( use virt_to_phys). >>Note For PCI addresses virt_to_phys doesn't work well. You must take the >>addresses from the "remap" function code. I did it and it works very well. > >Do you have a patch for you DMA support? No, but I will make one for the physical address lookup code, the small changes to support DMA in the kernel (access of EUMBAR base address) and the snippet of my code that I use in my driver. It will be against a 2.4.17 Kernel( sorry ) Note : I have A generic DMA driver but it has a big setup time of 25000 cycles making it interesting (better than memcpy) only for blocks larger than 2KBytes. ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/