Hi, one case that I forgot to mention: On Sun, 28 Aug 2011, Paul Walmsley wrote: > Several upstream device drivers get their DMA request line IDs from the > device data format[14][15][16]. But more drivers should be doing this > than currently are[17]: > > - the device driver author may have hardcoded the DMA request line ID, > assuming it would never change > > - DMA could be broken on the device due to hardware bugs, so it is unused > > - the driver author may just never have gotten around to implementing DMA, > or was reassigned to another project, or couldn't figure it out > > - the device may have its own internal DMA controller logic, so support > for an external DMA controller was simply never added - the driver may be using software-initiated DMA, which doesn't use a DMA request line, nor does it rely on the device to start or stop DMA. Instead, the CPU reprograms the DMA controller when the driver receives an interrupt - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
