linux-kernel - Re: [PATCH] net: fec: add post PHY reset delay DT property

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Message-ID: <20170522144301.GE29447@lunn.ch>
Date:   Mon, 22 May 2017 16:43:01 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Quentin Schulz <quentin.schulz@...e-electrons.com>
Cc:     fugang.duan@....com, robh+dt@...nel.org, mark.rutland@....com,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, thomas.petazzoni@...e-electrons.com
Subject: Re: [PATCH] net: fec: add post PHY reset delay DT property

On Mon, May 22, 2017 at 04:00:47PM +0200, Quentin Schulz wrote:
> Hi Andrew
> 
> On 22/05/2017 15:57, Andrew Lunn wrote:
> > On Mon, May 22, 2017 at 11:15:17AM +0200, Quentin Schulz wrote:
> >> Some PHY require to wait for a bit after the reset GPIO has been
> >> toggled. This adds support for the DT property `phy-reset-post-delay`
> >> which gives the delay in milliseconds to wait after reset.
> >>
> >> If the DT property is not given, no delay is observed. Post reset delay
> >> greater than 1000ms are invalid and are default to 1ms.
> > 
> > Hi Quentin
> > 
> > If it is invalid, please return -EINVAL.
> > 
> 
> Just copying the wording and behavior of phy-reset-duration. Should we
> then change the behavior of phy-reset-duration as well to return -EINVAL
> in that case or I just leave both as is?

No, you cannot change phy-reset-duration. There could be device tree
blobs out in the wild with invalid phy-reset-duration which silently
get converted to 1000ms by the code. You cannot break them.

However, you can prevent new additions which add invalid
phy-reset-post-delay.

    Andrew