Re: [PATCH v2 12/12] [UNTESTED] riscv: dts: starfive: beaglev-starlight: Enable gmac

From: Emil Renner Berthing <emil.renner.berthing@canonical.com>
To: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>,
	Emil Renner Berthing <emil.renner.berthing@canonical.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Emil Renner Berthing <kernel@esmil.dk>,
	Samin Guo <samin.guo@starfivetech.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Jose Abreu <joabreu@synopsys.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Richard Cochran <richardcochran@gmail.com>,
	Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, kernel@collabora.com
Subject: Re: [PATCH v2 12/12] [UNTESTED] riscv: dts: starfive: beaglev-starlight: Enable gmac
Date: Tue, 28 Nov 2023 17:09:41 +0100	[thread overview]
Message-ID: <CAJM55Z9+j6CmfjNkPLCk1DR3EBuEMspsRtNvygDbPWJDCytQpw@mail.gmail.com> (raw)
In-Reply-To: <054bbf2a-e7ba-40bf-8f8b-f0e0e9b396c6@collabora.com>

Cristian Ciocaltea wrote:
> On 11/28/23 14:08, Emil Renner Berthing wrote:
> > Cristian Ciocaltea wrote:
> >> On 11/26/23 23:10, Emil Renner Berthing wrote:
> >>> Cristian Ciocaltea wrote:
> >>>> The BeagleV Starlight SBC uses a Microchip KSZ9031RNXCA PHY supporting
> >>>> RGMII-ID.
> >>>>
> >>>> TODO: Verify if manual adjustment of the RX internal delay is needed. If
> >>>> yes, add the mdio & phy sub-nodes.
> >>>
> >>> Sorry for being late here. I've tested that removing the mdio and phy nodes on
> >>> the the Starlight board works fine, but the rx-internal-delay-ps = <900>
> >>> property not needed on any of my VisionFive V1 boards either.
> >>
> >> No problem, thanks a lot for taking the time to help with the testing!
> >>
> >>> So I wonder why you need that on your board
> >>
> >> I noticed you have a patch 70ca054e82b5 ("net: phy: motorcomm: Disable
> >> rgmii rx delay") in your tree, hence I you please confirm the tests were
> >> done with that commit reverted?
> >>
> >>> Also in the driver patch you add support for phy-mode = "rgmii-txid", but here
> >>> you still set it to "rgmii-id", so which is it?
> >>
> >> Please try with "rgmii-id" first. I added "rgmii-txid" to have a
> >> fallback solution in case the former cannot be used.
> >
> > Ah, I see. Sorry I should have read up on the whole thread. Yes, the Starlight
> > board with the Microchip phy works with "rgmii-id" as is. And you're right,
> > with "rgmii-id" my VF1 needs the rx-internal-delay-ps = <900> property too.
>
> That's great, we have now a pretty clear indication that this uncommon behavior
> stems from the Motorcomm PHY, and *not* from GMAC.
>
> >>
> >>> You've alse removed the phy reset gpio on the Starlight board:
> >>>
> >>>   snps,reset-gpios = <&gpio 63 GPIO_ACTIVE_LOW>
> >>>
> >>> Why?
> >>
> >> I missed this in v1 as the gmac handling was done exclusively in
> >> jh7100-common. Thanks for noticing!
> >>
> >>>>
> >>>> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> >>>> ---
> >>>>  arch/riscv/boot/dts/starfive/jh7100-beaglev-starlight.dts | 5 +++++
> >>>>  1 file changed, 5 insertions(+)
> >>>>
> >>>> diff --git a/arch/riscv/boot/dts/starfive/jh7100-beaglev-starlight.dts b/arch/riscv/boot/dts/starfive/jh7100-beaglev-starlight.dts
> >>>> index 7cda3a89020a..d3f4c99d98da 100644
> >>>> --- a/arch/riscv/boot/dts/starfive/jh7100-beaglev-starlight.dts
> >>>> +++ b/arch/riscv/boot/dts/starfive/jh7100-beaglev-starlight.dts
> >>>> @@ -11,3 +11,8 @@ / {
> >>>>  	model = "BeagleV Starlight Beta";
> >>>>  	compatible = "beagle,beaglev-starlight-jh7100-r0", "starfive,jh7100";
> >>>>  };
> >>>> +
> >>>> +&gmac {
> >>>> +	phy-mode = "rgmii-id";
> >>>> +	status = "okay";
> >>>> +};
> >>>
> >>> Lastly the phy-mode and status are the same for the VF1 and Starlight boards,
> >>> so why can't these be set in the jh7100-common.dtsi?
> >>
> >> I wasn't sure "rgmii-id" can be used for both boards and I didn't want
> >> to unconditionally enable gmac on Starlight before getting a
> >> confirmation that this actually works.
> >>
> >> If there is no way to make it working with "rgmii-id" (w/ or w/o
> >> adjusting rx-internal-delay-ps), than we should switch to "rgmii-txid".
> >
> > Yeah, I don't exactly know the difference, but both boards seem to work fine
> > with "rgmii-id", so if that is somehow better and/or more correct let's just go
> > with that.
>
> As Andrew already pointed out, going with "rgmii-id" would be the recommended
> approach, as this passes the responsibility of adding both TX and RX delays to
> the PHY.  "rgmii-txid" requires the MAC to handle the RX delay, which might
> break the boards having a conformant (aka well-behaving) PHY.  For some reason
> the Microchip PHY seems to work fine in both cases, but that's most likely an
> exception, as other PHYs might expose a totally different and undesired
> behavior.
>
> I will prepare a v3 soon, and will drop the patches you have already submitted
> as part of [1].

Sounds good. Then what's missing for ethernet to work is just the clock patches:
https://github.com/esmil/linux/commit/b5abe1cb3815765739aff7949deed6f65b952c4a
https://github.com/esmil/linux/commit/3a7a423b15a9f796586cbbdc37010d2b83ff2367

You can either include those as part of your patch series enabling ethernet, or
they can be submitted separately with the audio clocks. Either way is
fine by me.

/Emil

>
> Thanks again for your support,
> Cristian
>
> [1]: https://lore.kernel.org/all/20231126232746.264302-1-emil.renner.berthing@canonical.com/