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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:37426) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vlT8a-000000000BS-2Vfn; Thu, 29 Jan 2026 14:36:48 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1vlT8Y-0000000083Z-3wB7; Thu, 29 Jan 2026 14:36:46 +0000 Date: Thu, 29 Jan 2026 14:36:46 +0000 From: "Russell King (Oracle)" To: Vinod Koul Cc: Vincent Guittot , neil.armstrong@linaro.org, Simon Horman , krzk+dt@kernel.org, conor+dt@kernel.org, ciprianmarian.costea@oss.nxp.com, s32@nxp.com, p.zabel@pengutronix.de, ghennadi.procopciuc@nxp.com, Ionut.Vicovan@nxp.com, linux-phy@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, Frank.li@nxp.com Subject: Re: [PATCH 2/4] phy: s32g: Add serdes subsystem phy Message-ID: References: <20260126092159.815968-1-vincent.guittot@linaro.org> <20260126092159.815968-3-vincent.guittot@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260129_063658_153202_A137856A X-CRM114-Status: GOOD ( 20.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jan 29, 2026 at 08:00:38PM +0530, Vinod Koul wrote: > On 29-01-26, 13:51, Russell King (Oracle) wrote: > > On Thu, Jan 29, 2026 at 02:36:01PM +0100, Vincent Guittot wrote: > > > On Thu, 29 Jan 2026 at 14:23, Russell King (Oracle) > > > wrote: > > > > > > > > On Thu, Jan 29, 2026 at 02:01:13PM +0100, Vincent Guittot wrote: > > > > > yes, the usual pattern is : > > > > > - phy_set_mode_ext() > > > > > - then phy_power_on() > > > > > but I can add an additional check > > > > > > > > Please read Documentation/driver-api/phy/phy.rst section "Order of API > > > > calls" which suggests phy_set_mode_ext() after phy_power_on(). > > > > > > Fair enough. > > > That being said, all pcie drivers that use phy_set_mode_ext(), call > > > it before phy_power_on() > > > > It looks like many ethernet drivers do the same, so I think maybe the > > generic PHY documentation is incorrect or misleading, or is expressing > > a preference that almost no one follows. Something for the generic PHY > > maintainers to look at and/or comment on. > > I would feel it makes sense to configure the mode first and then power > the phy up. As commented above yes it looks like apart from one tegra > driver rest seem to do it this way. > > Lets update the documentation Please also indicate in the documentation whether changing the submode of the serdes (particularly for ethernet) is permitted without doing a phy_power_down()..phy_power_up() dance around the phy_set_mode_ext() call. Thanks. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!