On Sat, Jan 04, 2014 at 03:59:46PM -0800, Ravi Patel wrote: > On Sat, Dec 21, 2013 at 11:03 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Saturday 21 December 2013 17:00:51 Loc Ho wrote: > >> On Sat, Dec 21, 2013 at 12:11 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > >> > On Saturday 21 December 2013, Ravi Patel wrote: > >> >> This patch adds support for APM X-Gene SoC Queue Manager/Traffic Manager. > >> >> QMTM is required by APM X-Gene SoC Ethernet, PktDMA (XOR Engine) and > >> >> Security Engine subsystems. All subsystems communicate with QMTM using > >> >> messages which include information about the work to be performed and > >> >> the location of associated data buffers. > >> > > >> > Please describe here what the purpose of the qmtm is, as this is not > >> > entirely clear from the code. > >> > > >> > In particular, please describe how this differs from a dmaengine driver > >> > and why it is not possible to extend the dma slave API to describe qmtm > >> > as a dma engine. > >> > > >> [Loc Ho] > >> If the QM driver implements the DMA API, what about the actual DMA > >> engine driver which interfaces with this QM driver. We would have DMA > >> client interfaces with the X-Gene DMA driver (not available yet) via > >> DMA API which in turn interfaces with this QM driver via DMA API. > >> Won't this be kind of awkward? Also, the QM only manage messages (or > >> descriptors) which are 32-bytes or 64-bytes. It doesn't actually do > >> any data transfer of various sizes. > > > > Please describe here what the purpose of the qmtm is, as this is not > > entirely clear from the code or from your reply. > > > > Greg was guessing that it's a bus controller, my best guess is a DMA > > engine. If it's something completely different, you have to let > > us know what it is so we can do a proper review rather than guessing. > > > > Please provide a link to the data sheet if you are unable to explain. > > Here is URL to a text document explaining role of QMTM device with CPU, Ethernet > subsystem. > > https://drive.google.com/file/d/0B28TgQZ3JLoRRGNnbjJoUGNHWW8/edit?usp=sharing There is nothing at this link :( > PktDMA and Security subsystem interfaces with QMTM in the same way as Ethernet. How does a "security" subsystem have anything to do with ethernet? confused, greg k-h -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
