[PATCH V2 0/4] misc: xgene: Add support for APM X-Gene SoC Queue Manager/Traffic Manager

[Ravi Patel]

On Sun, Jan 5, 2014 at 10:01 AM, Greg KH <gregkh at linuxfoundation.org> wrote:
> On Sat, Jan 04, 2014 at 09:39:08PM -0800, Loc Ho wrote:
>> Hi,
>>
>> >> >> >> 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 :(
>>
>> I tried click on the txt file link from web site
>> http://www.spinics.net/lists/netdev/msg264628.html and don't see any
>> problem with accessing the txt file.
>
> Now it's working :)
>
> Anyway, as this is a .txt file, why wasn't it just sent in email, and
> added to the patch series as a documentation file?

Sure I will include the text documentation to an appropriate place in the
Documentation directory in my next version of QMTM patch.