Re: [net: PATCH] net: mvpp2: disable link IRQ waiting for IDLE frames

[David Miller]

From: Marcin Wojtas <mw@xxxxxxxxxxxx>
Date: Tue, 23 Apr 2019 18:08:00 +0200

> Hi David, Rusell,
> 
> czw., 28 lut 2019 o 14:58 Marcin Wojtas <mw@xxxxxxxxxxxx> napisał(a):
>>
>> Hi Russell,
>>
>> czw., 28 lut 2019 o 10:36 Russell King - ARM Linux admin
>> <linux@xxxxxxxxxxxxxxx> napisał(a):
>> >
>> > On Wed, Feb 27, 2019 at 06:47:32PM +0100, Marcin Wojtas wrote:
>> > > Current version of the driver was configuring XLG MAC
>> > > in a way to wait 3 IDLE frames before allowing for the
>> > > link-up interrupt to be triggered. This resulted in an
>> > > issue, preventing to detect the link change during RX
>> > > traffic on the interface. Fix that.
>> >
>> > What about noise sensitivity?  Does this now mean that on boards such as
>> > Macchiatobin Single Shot or Clearfog GT9k where the serdes is connected
>> > directly to a SFP cage, that noise on the serdes lines triggers a link
>> > indication?
>> >
>>
>> Afaik waiting for idle frames is not required by any standard. In fact
>> this feature of the XLG MAC caused a risk that after dropping the link
>> during data transfer it would never go up again until remote peer
>> stops it.
>>
>> I tested it on 3 different boards with SerDes directly connected to
>> the SFP cage and I'm also not aware of any reporte about
>> noise-triggered false link interrupts in XLG MAC (proprietary Marvell
>> mvpp2x driver did not use waiting 3 idle frames feature). I'd rather
>> assume the MAC is not vulnerable to it, and only properly established
>> link can trigger an event.
>>
> 
> This patch seems to get forgotten - any objections to merge it?

If there is agreement, please repost it.

Thank you.