On Fri, May 02, 2014 at 01:08:27PM -0500, Andy Gross wrote: > On Fri, May 02, 2014 at 09:58:41PM +0530, Vinod Koul wrote: > > On Thu, Apr 17, 2014 at 05:04:02PM -0500, Andy Gross wrote: > > > This patch adds APIs that allow for BAM hardware flags to be set per > > > descriptor. Each one of the new flags informs the attached peripheral of a > > > special behavior that is required. > > > > > > The EOT flag requests that the peripheral assert an end of transaction interrupt > > > when that descriptor is complete. It also results in special signaling protocol > > > that is used between the attached peripheral and the core using the DMA > > > controller. > > DMA_PREP_INTERRUPT ?? > > I have 3 different IRQs that can be asserted based on the bit I set in the > hardware descriptor. The normal IRQ is the INT bit. However, in some cases the > peripheral protocol requires the use of the EOT or EOB interrupt instead. The > DMA_PREP_INTERRUPT would only work if I had only 2 choices. Thinking about this more, I could use the DMA_PREP_INTERRUPT to cover the EOT flag. However, I might get in a bind later if I need to support the EOB (end of block) interrupt. > > > > > > > > > The NWD flag requests that the peripheral wait until the data has been fully > > > processed before signaling an interrupt. > > interrupt for transaction complete or DMA request? > > This is a special signaling mechanism that holds off the DMA interrupt until the > peripheral actually acks that the data has been processed completely. This is > required in many cases by the peripheral. One example is the SPI controller. > At the end of a transaction you are supposed to set the NWD so that the chip > select is de-asserted. I'm not sure what flag I could map this to... maybe DMA_CTRL_ACK? or maybe the DMA_PREP_FENCE? I don't generally like overloading the flags and slightly twisting their intent. Could we add a flag to denote device ACK? -- sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation -- 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
