From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudheer.v Date: Fri, 19 Oct 2018 12:41:56 +0530 Subject: [[PATCH] 8/9] DMA-UART-Driver-for-AST2500 In-Reply-To: References: <1539749466-3912-1-git-send-email-open.sudheer@gmail.com> <1539749466-3912-9-git-send-email-open.sudheer@gmail.com> <20181017060531.GU2400@vkoul-mobl> <351eecd5b1b21893e94f76b34c058c6257b7f837.camel@kernel.crashing.org> <20181018095507.GC2400@vkoul-mobl> Message-ID: <20181019071154.GE13642@Pilot130> List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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. Thank you. -- Sudheer