Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode

From: Peter Ujfalusi <peter.ujfalusi@ti.com>
To: Niklas Cassel <niklas.cassel@linaro.org>,
	Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Vinod Koul <vkoul@kernel.org>,
	David S Miller <davem@davemloft.net>,
	<linux-arm-msm@vger.kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	<netdev@vger.kernel.org>, "Nori, Sekhar" <nsekhar@ti.com>
Subject: Re: [PATCH] net: phy: at803x: disable delay only for RGMII mode
Date: Thu, 14 Feb 2019 12:49:36 +0200	[thread overview]
Message-ID: <3356ff05-8d08-591e-03bf-9d846f79097b@ti.com> (raw)
In-Reply-To: <20190213174034.GA6954@centauri.lan>

Hi Niklas,

On 13/02/2019 19.40, Niklas Cassel wrote:
> On Wed, Feb 13, 2019 at 02:40:18PM +0100, Marc Gonzalez wrote:
>> On 13/02/2019 14:29, Andrew Lunn wrote:
>>
>>>> So we have these modes:
>>>>
>>>> PHY_INTERFACE_MODE_RGMII: TX and RX delays disabled
>>>> PHY_INTERFACE_MODE_RGMII_ID: TX and RX delays enabled
>>>> PHY_INTERFACE_MODE_RGMII_RXID: RX delay enabled, TX delay disabled
>>>> PHY_INTERFACE_MODE_RGMII_TXID: TX delay enabled, RX delay disabled
>>>>
>>>> What I don't like with this patch, is that if we specify phy-mode
>>>> PHY_INTERFACE_MODE_RGMII_TXID, this patch will enable TX delay,
>>>> but RX delay will not be explicitly set.
>>>
>>> That is not the behaviour we want. It is best to assume the device is
>>> in a random state, and correctly enable/disable all delays as
>>> requested. Only leave the hardware alone if PHY_INTERFACE_MODE_NA is
>>> used.
>>
>> That's what my patch did:
>> https://www.spinics.net/lists/netdev/msg445053.html
>>
>> But see Florian's remarks:
>> https://www.spinics.net/lists/netdev/msg445133.html
> 
> Hello Marc,
> 
> I saw that comment from Florian. However that was way back in 2017.
> Maybe the phy-modes were not as well defined back then?
> 
> Andrew recently suggested to fix the driver so that it conforms with the
> phy-modes, and fix any SoC that specified an incorrect phy-mode in DT
> and thus relied upon the broken behavior of the PHY driver:
> https://www.spinics.net/lists/netdev/msg445133.html
> 
> 
> So, I've rebased your old patch, see attachment.
> I suggest that Peter test it on am335x-evm.

with the patch + s/rgmii-txid/rgmii-id in the am335x-evmsk.dts ethernet
is working.
I don't have am335x-evm to test, but it has the same PHY as evmsk.

> am335x-evm appears to rely on the current broken behavior of the PHY
> driver, so we will probably need to fix the am335x-evm according to this:
> https://www.spinics.net/lists/netdev/msg445117.html
> and merge that as well.
> 
> 
> Andrew, Florian, do you both agree?
> 
> 
> Kind regards,
> Niklas
> 

- Péter

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