On Sat, Oct 20, 2018 at 09:56:24PM +0530, Vinod wrote: > On 19-10-18, 12:41, sudheer.v wrote: > > On Fri, Oct 19, 2018 at 10:32:24AM +1100, Benjamin Herrenschmidt wrote: > > > On Thu, 2018-10-18 at 15:25 +0530, Vinod wrote: > > > > > > > > > It's not a dmaengine driver. It's a serial UART driver that happens to > > > > > use a dedicated DMA engine. > > > > > > > > Then I see no reason for it to use dmaengine APIs. The framework allows > > > > people to share a controller for many clients, but if you have dedicated > > > > one then you may use it directly > > > > > > Well... the engine is shared by a few UARTs, they have dedicated rings > > > but there's a common set of regs for interrupt handling etc. > > > > > > That said, I still think it could be contained within a UART driver, > > > there's little benefit in adding the framework overhead, esp since > > > these are really weak cores, any overhead will be felt. > > > > > > Ben. > > > > > > > > It's unclear whether it should be split into two drivers, or just have > > > > > the serial driver directly use the dma engine since that engine is > > > > > dedicated in HW to only work on those UARTs and nothing else... > > > > > > > > > > Cheers, > > > > > Ben. > > > > Initially we wanted to have a single driver, > > however we had an informal discussion with one of the maintainer > > and based on the feedback, followed the Linux DMA and UART architecture. > > > > If this seperate DMA-engine driver adds more overhead than benifit, > > we will merge them into a single UART driver and resubmitt the patches. > > Vinod, > > can this dma-controller driver sit under dma subsystem?. > > or better to move it under UART framework. > > > My advise would be to see what you can do with the DMA IP block. If this > can/would be used in different places then it would make sense to do a > dmaengine driver and solve the problem for everyone. > > If this is always going to be hidden behind serial then maybe it makes > sense to be inside serial driver and not use dmaengine APIs > > If you decide to prefer the former case, please move it to dmaengine and > resubmit :) > > HTH > -- > ~Vinod Hi All, As the DMA engine is dedicated only to UART,we have decided to rewrite the driver so that no code will come under drivers/dma. I will resubmitt the patches after merging dma controller code and uart driver code. Regards -sudheer
