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From: Andrew Lunn <andrew@lunn.ch>
To: POPESCU Catalin <catalin.popescu@leica-geosystems.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"pabeni@redhat.com" <pabeni@redhat.com>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"krzysztof.kozlowski+dt@linaro.org"
	<krzysztof.kozlowski+dt@linaro.org>,
	"conor+dt@kernel.org" <conor+dt@kernel.org>,
	"afd@ti.com" <afd@ti.com>,
	"hkallweit1@gmail.com" <hkallweit1@gmail.com>,
	"linux@armlinux.org.uk" <linux@armlinux.org.uk>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	GEO-CHHER-bsp-development
	<bsp-development.geo@leica-geosystems.com>,
	"m.felsch@pengutronix.de" <m.felsch@pengutronix.de>
Subject: Re: [PATCH v2 2/2] net: phy: dp83826: support TX data voltage tuning
Date: Thu, 8 Feb 2024 14:56:33 +0100	[thread overview]
Message-ID: <145e1c28-af2b-4aca-9fd3-f9d7a272516c@lunn.ch> (raw)
In-Reply-To: <f37e9df4-e1bd-4d40-bd99-3998cfd803f4@leica-geosystems.com>

> > I could be reading this wrong, but it looks like
> > DP83826_CFG_DAC_MINUS_DEFAULT actually means leave the value
> > unchanged? Is there anything guaranteeing it does in fact have the
> > default value in the hardware?
> >
> >          Andrew
> 
> Yes, the datasheet clearly states the default/reset values of both 
> registers VOD_CFG1 & VOD_CFG2 which are :
> - cfg_dac_minus : 30h
> - cfg_dac_plus : 10h

And the device is actually and always reset by Linux when the driver
loads? Anything the bootloader has done, or a previous kernel, will be
cleared?

Please add this explanation to the commit message.

I'm being pedantic because we have had problems like this in the past.
If a register was not actually set back to the default value, the
bootloader set it to some other value, the board can work fine. Then a
board can came along which the bootloader set the wrong value, and the
default is actually needed. Fixing the driver to actually enforce the
default breaks boards...

	 Andrew

  reply	other threads:[~2024-02-08 13:56 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-07 17:58 [PATCH v2 1/2] dt-bindings: net: dp83826: support TX data voltage tuning Catalin Popescu
2024-02-07 17:58 ` [PATCH v2 2/2] net: phy: " Catalin Popescu
2024-02-07 18:35   ` Andrew Lunn
2024-02-08  8:58     ` POPESCU Catalin
2024-02-08 13:56       ` Andrew Lunn [this message]
2024-02-08 16:14         ` POPESCU Catalin
2024-02-08 16:50           ` Andrew Lunn
2024-02-08 16:54             ` POPESCU Catalin
2024-02-08  7:35 ` [PATCH v2 1/2] dt-bindings: net: " Krzysztof Kozlowski
2024-02-08  8:48   ` POPESCU Catalin
2024-02-08  8:50     ` Krzysztof Kozlowski
2024-02-08  9:08       ` POPESCU Catalin
2024-02-08  9:12         ` Krzysztof Kozlowski
2024-02-08  9:19           ` POPESCU Catalin

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