Re: [RFC PATCH 0/3] net: macb: Wake-on-Lan magic packet fixes

[Nicolas Ferre]

Hi Harini,

On 03/04/2020 at 15:36, Harini Katakam wrote:
> Hi Nicolas,
>
> On Fri, Apr 3, 2020 at 6:45 PM <nicolas.ferre@xxxxxxxxxxxxx> wrote:
> > From: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
> >
> > Hi,
> > Here are some of my early patches in order to fix WoL magic-packet on the
> > current macb driver.
> > Addition of this feature to GEM types of IPs is yet to come. I would like to
> > have your feedback on these little patches first so that I can continue
> > investigating the addition of GEM WoL magic-packet.
> >
> > Harini, I know that you have patches for GEM in order to integrate WoL ARP
> > mode [1]. I'll try to integrate some of your work but would need that this feature
> > is better integrated in current code. For instance, the choice of "magic
> > packet" or "ARP" should be done by ethtool options and DT properties. For
> > matching with mainline users, MACB and GEM code must co-exist.
>
> Agree. I'll try to test this series and get back to you next week.
>
> > The use of dumb buffers for RX seems also fairly platform specific and we would
> > need to think more about it.
>
> I know that the IP versions from r1p10 have a mechanism to disable DMA queues
> (bit 0 of the queue pointer register) which is cleaner. But for
> earlier IP versions,

Which IP name are you referring to? GEM, GEM-GXL? What is the value of 
register 0xFC then?

> I remember discussing with Cadence and there is no way to keep RX
> enabled for WOL
> with RX DMA disabled. I'm afraid that means there should be a bare
> minimum memory
> region with a dummy descriptor if you do not want to process the
> packets. That memory
> should also be accessible while the rest of the system is powered
> down. Please let me

Very interesting information Harini, thanks a lot for having shared it.

My GEM IP has 0xFC at value: 0x00020203. But I don't see a way to keep 
DMA queues disabled by using the famous bit that you mention above.

> know if you think of any other solution.

I'm trying all this right now. I keep you posted.

Thanks and best regards,
  Nicolas


--
Nicolas Ferre