Re: [PATCH net-next 0/5] Flow control for NXP ENETC

From: Michael Walle <michael@walle.cc>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	netdev@vger.kernel.org, Po Liu <po.liu@nxp.com>,
	Claudiu Manoil <claudiu.manoil@nxp.com>,
	Alex Marginean <alexandru.marginean@nxp.com>,
	Rob Herring <robh+dt@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	Russell King - ARM Linux admin <linux@armlinux.org.uk>,
	Andrew Lunn <andrew@lunn.ch>,
	Vladimir Oltean <vladimir.oltean@nxp.com>
Subject: Re: [PATCH net-next 0/5] Flow control for NXP ENETC
Date: Tue, 20 Apr 2021 16:10:34 +0200	[thread overview]
Message-ID: <0bf4aa61dea7be0723fda2d8597644ad@walle.cc> (raw)
In-Reply-To: <20210420140433.hajuvfiz4humhhkt@skbuf>

Hi Vladimir,

Am 2021-04-20 16:04, schrieb Vladimir Oltean:
> On Tue, Apr 20, 2021 at 03:27:24PM +0200, Michael Walle wrote:
>> Hi Vladimir,
>> 
>> Am 2021-04-17 01:42, schrieb Vladimir Oltean:
>> > From: Vladimir Oltean <vladimir.oltean@nxp.com>
>> >
>> > This patch series contains logic for enabling the lossless mode on the
>> > RX rings of the ENETC, and the PAUSE thresholds on the internal FIFO
>> > memory.
>> >
>> > During testing it was found that, with the default FIFO configuration,
>> > a sender which isn't persuaded by our PAUSE frames and keeps sending
>> > will cause some MAC RX frame errors. To mitigate this, we need to ensure
>> > that the FIFO never runs completely full, so we need to fix up a setting
>> > that was supposed to be configured well out of reset. Unfortunately this
>> > requires the addition of a new mini-driver.
>> 
>> What happens if the mini driver is not enabled? Then the fixes aren't
>> applied and bad things happen (now with the addition of flow control),
>> right?
>> 
>> I'm asking because, if you have the arm64 defconfig its not enabled.
>> 
>> shouldn't it be something like:
>> 
>> diff --git a/drivers/net/ethernet/freescale/enetc/Kconfig
>> b/drivers/net/ethernet/freescale/enetc/Kconfig
>> index d88f60c2bb82..cdc0ff89388a 100644
>> --- a/drivers/net/ethernet/freescale/enetc/Kconfig
>> +++ b/drivers/net/ethernet/freescale/enetc/Kconfig
>> @@ -2,7 +2,7 @@
>>  config FSL_ENETC
>>         tristate "ENETC PF driver"
>>         depends on PCI && PCI_MSI
>> -       depends on FSL_ENETC_IERB || FSL_ENETC_IERB=n
>> +       select FSL_ENETC_IERB
>>         select FSL_ENETC_MDIO
>>         select PHYLINK
>>         select PCS_LYNX
> 
> Yes, ideally the IERB driver and the ENETC PF driver should be built in
> the same way, or the IERB driver can be built-in and the PF driver can
> be module. I don't know how to express this using Kconfig, sorry.

With the small patch above it is:
  FSL_ENETC=m -> FSL_ENETC_IERB = m or y
  FSL_ENETC=y -> FSL_ENETC_IERB = y
  FSL_ENETC=n -> FSL_ENETC_IERB = m,y or n

Will you fix it? Should I prepare a patch?

-michael

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