Re: About adding support for MT76x2U to Linux kernel

[Felix Fietkau <nbd@openwrt.org>]

On 2016-03-08 13:49, Johannes Stezenbach wrote:
> On Mon, Mar 07, 2016 at 10:22:38PM +0100, Felix Fietkau wrote:
>> On 2016-03-07 13:41, Johannes Stezenbach wrote:
>> > http://www.mediatek.com/en/downloads1/downloads/mt7612u/
>> I checked, they simply use a software timer for it and stuff buffered
>> multicast packets into the BE queue. I don't think the hardware offers
>> any better way of doing this...
> 
> I had to refresh my memory on this driver.  The thing that tripped
> me when I first read through it was that is using a jiffies based
> timer and additionally sets it to fire 10ms after the calculated
> beacon time.  So it's always too late, isn't it?
> 
> But of course it is irrelevant for us since we can use a hrtimer.
> However, if other frames are queued in the hw they are still sent
> before the buffered frames.  Since the hw has a dedicated queue
> for HCCA I wonder if it could be used here?
> (My knowledged of the standard is also rusty, ISTR the buffered
> traffic must be sent before other traffic before the stations
> go back to sleep.)
On mt76x2e, I simply use the management queue for buffered frames, since
it has a very high priority, and management frames are typically
delivered via the voice WMM queue anyway.
I think the MAC is probably similar enough that the same approach is
possible on mt76x2u as well.

- Felix