From mboxrd@z Thu Jan 1 00:00:00 1970 From: dan.j.williams@intel.com (Dan Williams) Date: Thu, 25 Mar 2010 16:12:46 -0700 Subject: [PATCH v2] PL330: Add PL330 DMA controller driver In-Reply-To: <1b68c6791003251527s1ef985d2m4a309a3c09e31e0a@mail.gmail.com> References: <4BAAD5BB.7050101@samsung.com> <1b68c6791003242234h106d9530p12b5a046a906227e@mail.gmail.com> <63386a3d1003250130w6f34854ag2ca163799e9b7bed@mail.gmail.com> <1b68c6791003250517y4e2789baoe147e5982c363682@mail.gmail.com> <4BAB7D9F.4070807@intel.com> <1b68c6791003251527s1ef985d2m4a309a3c09e31e0a@mail.gmail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Mar 25, 2010 at 3:27 PM, jassi brar wrote: > On Fri, Mar 26, 2010 at 12:13 AM, Dan Williams wrote: >> jassi brar wrote: >>>> >>>> Perhaps Joonyoung can simply port over the stuff >>>> you need to this driver if you show your code. >>> >>> Having worked on Samsung SoCs(with PL330 DMAC) based products, I would be >>> _very_ surprised if any user found this implementation useful. >>> Let alone testing, this implementation can't even explain usability >>> for fast peripherals >>> with shallow FIFOs. I didn't give feedback for this patch because I am >>> not sure if this >>> is the right way to go at all. >> >> This is the wrong attitude. ?If it were not for a simple oversight >> Joonyoung's driver would already be upstream for the past two kernel >> releases. ?So you need to work together to improve that driver to >> incorporate what you need. > Nothing wrong in attitude here. > Giving feedback on the code only comes after one is convinced with the > overall approach taken. The last time I raised the PL330 driver issue, > most people were not enthusiastic with this drivers/dma/ approach. > I wasn't active mainline discussions when the driver was originally > submitted a few months ago. > And now my replies are not very 'polite' because theres a lot going on > in the background that people in public threads don't know about. Thanks for clarifying. > > >> It sounds like you just need to add an extension for the arch specific dma >> api. > I actually plan more than that. > Apart from inefficient design, JoonYoung's driver has made some fatal > assumptions > about PL330, which will result in DMA aborts if used with SoCs that implement > configuration of PL330 that is very different from Samsung SoCs' > Of course, I address all such issues that I can think of, in my implementation. Ok, I'll rely on acked-by's from the interested parties once your driver is out as I do not have a vested interest in this hardware, just the dmaengine framework issues. -- Dan