>-----Original Message----- >From: Mike Frysinger [mailto:[email protected]] >Sent: Wednesday, February 04, 2009 6:04 PM >To: Hennerich, Michael >Cc: [email protected]; [email protected] >Subject: Re: [Linux-kernel-commits] >[6057]trunk/drivers/mtd/nand/bf5xx_nand.c: bug[4833] The DMAs havedifferent >size on BF52x and BF54x > >On Wed, Feb 4, 2009 at 11:54, Hennerich, Michael wrote: >>>where in the HRM do you see it saying "32-bit dma is not supported" ? >> >> I don't think it's explicitly written in the NFC chapter of the HRM. >> But it's a matter of fact that the DMA DAB is 16-bit on BF52x. >> >> From the PHRM: >> >> "The 16-bit DMA Access Bus (DAB) connects the DMA controller to the >> on-chip peripherals, PPI, SPI, Ethernet MAC, the SPORTs, NFC, >> HOSTDP and the UARTs." >> >> 32-bit DMA won't work! > >the sport controller supports 32bit dma (and our drivers are using >it). same goes for ethernet mac.
Well right. Some peripherals support 32-bit DMA over an 16-bit DAB (taking 2x cycles) , some not. NFC is one that doesn't support this. Whole story - Cliff skyped me this morning about the BF52x NFC DMA problem. In return I called Andrew C. and asked him about the NFC and associated software differences between NFC on 54x and 52x. Straight came the answer BF52x DMA must be WDSIZE_16 !!! -Michael >-mike _______________________________________________ Linux-kernel-commits mailing list [email protected] http://blackfin.uclinux.org/mailman/listinfo/linux-kernel-commits
