On Friday 25 September 2015 16:17:29 Jon Hunter wrote: > On 25/09/15 16:03, Arnd Bergmann wrote: > > On Friday 25 September 2015 15:56:40 Jon Hunter wrote: > >> + case DMA_MEM_TO_DEV: > >> + burst_size = fls(tdc->config.dst_maxburst); > >> + ch_regs->config = ADMA_CH_CONFIG_SRC_BUF(num_bufs - 1); > >> + ch_regs->ctrl = ADMA_CH_CTRL_XFER_DIR(ADMA_MEM_TO_AHUB) | > >> + ADMA_CH_CTRL_TX_REQ(tdc->config.slave_id); > >> + ch_regs->src_addr = buf_addr; > >> + break; > >> + > >> + case DMA_DEV_TO_MEM: > >> + burst_size = fls(tdc->config.src_maxburst); > >> + ch_regs->config = ADMA_CH_CONFIG_TRG_BUF(num_bufs - 1); > >> + ch_regs->ctrl = ADMA_CH_CTRL_XFER_DIR(ADMA_AHUB_TO_MEM) | > >> + ADMA_CH_CTRL_RX_REQ(tdc->config.slave_id); > >> + ch_regs->trg_addr = buf_addr; > >> + break; > > > > Do not use the 'slave_id' field here to identify the slave device, that > > concept is broken. Instead, put the slave identification into the > > dma specifier in DT and read it out in your xlate function. > > Why is it broken? This requires the slave driver to pass a slave id through the dmaengine_slave_config() interface, but we don't want the driver to know how it is connected to the dma engine. That information is not a property of the slave itself but rather of the connection between the slave and the master, and it belongs into DT, similar to how we deal with IRQ or GPIO numbers. > What happens if I don't know the slave-id? In other words, the slave-id > can be dynamically allocated and associated with a given slave. How do you identify the slave that the slave-id is associated with? Arnd -- 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
