HI Vinod, > -----Original Message----- > From: Vinod Koul [mailto:vinod.koul@xxxxxxxxx] > Sent: Saturday, June 27, 2015 8:11 PM > To: Appana Durga Kedareswara Rao > Cc: dan.j.williams@xxxxxxxxx; Michal Simek; Soren Brinkmann; Anirudha > Sarangi; Punnaiah Choudary Kalluri; dmaengine@xxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Srikanth Thokala > Subject: Re: [PATCH v7] dma: Add Xilinx AXI Direct Memory Access Engine > driver support > > On Wed, Jun 24, 2015 at 05:12:13PM +0000, Appana Durga Kedareswara Rao > wrote: > > > where is the hardware addr programmed? I can see you are using sg > > > list passed for porgramming one side of a transfer where is other > > > side programmed? > > > > The actual programming happens in the start_transfer(I mean in > > issue_pending) API There are two modes > > > > All the h/w addresses are configured in the start_transfer API. > > > > In simple transfer Mode the below write triggers the transfer > > dma_ctrl_write(chan, XILINX_DMA_REG_BTT, > > hw->control & > > XILINX_DMA_MAX_TRANS_LEN); > > > > In SG Mode the below write triggers the transfer. > > dma_ctrl_write(chan, XILINX_DMA_REG_TAILDESC, tail->phys); > > > > There are two Channels MM2S (Memory to device) and S2MM (Device to > Memory) channel. > > --> In MM2S case we need to configure the SOF (Start of frame) for the > > --> first BD and we need to set EOF(end of frame) for the last BD For > > --> S2MM case no need to configure SOF and EOF. Once we got the IOC > > --> interrupt will call mark the cookie as complete and will > > Call the user callback. There users checks for the data. > > > > Please let me know if you are not clear. > No sorry am not... > > I asked how the device address in configured. For both MM2S S2MM you are > using sg for memory address, where are you getting device adress, are you > assuming/hardcoding or getting somehow, if so how? As Nicolae Rosia explained there is no concept of address for this DMA. Connections are made at the design time. http://www.fpgadeveloper.com/wp-content/uploads/2014/08/fpga_developer_20140806_130447.png > > > > no dma_slave_config handler? > > No need of this callback earlier in the dma_slave_config we are doing > > terminate_all Now we have a separate API for that so no need to have this > call back. > > The question was on parameters There is no address related parameters need to configure for this DMA. That's why no need of dma_slave_config handler. Regards, Kedar. > > -- > ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
