Arnd Bergmann <arnd@xxxxxxxx> writes: > On Tue, Apr 3, 2018 at 10:19 PM, Robert Jarzmik <robert.jarzmik@xxxxxxx> wrote: >> ... chop chop removing unneeded recipients .... >> >> Arnd Bergmann <arnd@xxxxxxxx> writes: >>> It still feels odd to me that there is an entry in the slave map for >>> a device that does not have a request line. However, it also seems >>> that the entire code in those two drivers that deals with DMA is specific >>> to PXA anyway, so maybe it can be done differently: instead of >>> calling dma_request_slave_channel_compat() or dma_request_chan() >>> with a fake request line, how about calling dma_request_channel() >>> with an NULL filter function and data, and have the driver handle >>> the empty data case the same way as the rq=-1 case today? >> Okay, in this case : >> - the channel priority cannot be passed anymore > > Right, but it could just always use a static priority, right? Yes, an implicit default priority. I'm not a big fan of implicit parameters, yet I can do it. >> - and I don't see how this can work : >> dma_request_channel() >> __dma_request_channel() >> find_candidate() >> private_candidate(mask, device, fn, fn_param); >> /* Here, fn == NULL and fn_param == NULL as per your proposal */ >> >> This function will find the first available dma channel, all right, but >> no function will be called in pxa_dma driver, and therefore the last >> requestor of the channel will be used, which is bad. > > Can't you just reset those in pxad_free_chan_resources()? I can, let's see what happens next ... Cheers. -- Robert -- 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
