Re: [PATCH net-next v3 01/10] net: stmmac: move XPCS lifetime management to platform drivers

From: Maxime Chevallier <maxime.chevallier@bootlin.com>
To: Coia Prant <coiaprant@gmail.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>, Vinod Koul <vkoul@kernel.org>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
	Romain Gantois <romain.gantois@bootlin.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Russell King <linux@armlinux.org.uk>,
	Shawn Lin <shawn.lin@rock-chips.com>,
	David Heidelberg <david@ixit.cz>,
	netdev@vger.kernel.org, linux-rockchip@lists.infradead.org,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH net-next v3 01/10] net: stmmac: move XPCS lifetime management to platform drivers
Date: Thu, 3 Sep 2026 10:58:54 +0200	[thread overview]
Message-ID: <7d0e6b70-b474-44d9-bf57-6079b8d9651e@bootlin.com> (raw)
In-Reply-To: <CALj3r0i2msRXH-uqA2QX=cRkQwM_H2bFH9GiroEys2NfEbTtCQ@mail.gmail.com>

On 9/3/26 10:51, Coia Prant wrote:
> Maxime Chevallier <maxime.chevallier@bootlin.com> 于2026年9月3日周四 16:32写道：
>>
>> Hi again,
>>
>> Sorry I had a second look at that after a good night's sleep, and actually here
>> we may regress. The original logic checked for "pcs-handle" presence, then
>> for the pcs mask, but if no PCS is found we didn't error out, we returned 0.
>>
>> This is making it mandatory to have a PCS. Please handle gracefully the "there's no
>> PCS" case :(
>>
>>
>> Maxime
> 
> Hi,
> 
> This change covers all callbacks that use `select_pcs`. Drivers
> without `select_pcs` callbacks will not have their pcs used by
> Phylink.
> 
> Currently, only the Intel mgbe driver uses xpcs, and Intel has also
> set a mask for pcs-handle not set.
> 
> This means that on Intel platforms, the parts that implement
> `select_pcs` always require xpcs to exist.
> 
> I think there shouldn't be any problems here, but I agree with you,
> regression issues can indeed easily occur here.

Alight, let's keep it this way. The assumption becomes "if you have
a pcs_init() callback, it means you expect a PCS to be there, ENODEV
is an actual error".

My reviewed-by still stands then.

Maxime

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