linux-kernel - RE: [PATCH v2] net: fec: add post PHY reset delay DT property

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Date:   Thu, 1 Jun 2017 05:39:53 +0000
From:   Andy Duan <fugang.duan@....com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Rob Herring <robh@...nel.org>,
        Quentin Schulz <quentin.schulz@...e-electrons.com>
CC:     "mark.rutland@....com" <mark.rutland@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "thomas.petazzoni@...e-electrons.com" 
        <thomas.petazzoni@...e-electrons.com>
Subject: RE: [PATCH v2] net: fec: add post PHY reset delay DT property

From: Florian Fainelli <f.fainelli@...il.com> Sent: Thursday, June 01, 2017 9:53 AM
>To: Andy Duan <fugang.duan@....com>; Rob Herring <robh@...nel.org>;
>Quentin Schulz <quentin.schulz@...e-electrons.com>
>Cc: mark.rutland@....com; netdev@...r.kernel.org;
>devicetree@...r.kernel.org; linux-kernel@...r.kernel.org;
>thomas.petazzoni@...e-electrons.com
>Subject: Re: [PATCH v2] net: fec: add post PHY reset delay DT property
>
>Le 05/31/17 à 18:39, Andy Duan a écrit :
>> From: Rob Herring <robh@...nel.org> Sent: Thursday, June 01, 2017
>> 12:44 AM
>>> On Tue, May 23, 2017 at 11:48:08AM +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.
>>>>
>>>> Signed-off-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
>>>> ---
>>>>
>>>> v2:
>>>>   - return -EINVAL when phy-reset-post-delay is greater than 1000ms
>>>>   instead of defaulting to 1ms,
>>>>   - remove `default to 1ms` when phy-reset-post-delay > 1000Ms from DT
>>>>   binding doc and commit log,
>>>>   - move phy-reset-post-delay property reading before
>>>>   devm_gpio_request_one(),
>>>>
>>>>  Documentation/devicetree/bindings/net/fsl-fec.txt |  4 ++++
>>>>  drivers/net/ethernet/freescale/fec_main.c         | 16 +++++++++++++++-
>>>>  2 files changed, 19 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt
>>>> b/Documentation/devicetree/bindings/net/fsl-fec.txt
>>>> index a1e3693cca16..6f55bdd52f8a 100644
>>>> --- a/Documentation/devicetree/bindings/net/fsl-fec.txt
>>>> +++ b/Documentation/devicetree/bindings/net/fsl-fec.txt
>>>> @@ -15,6 +15,10 @@ Optional properties:
>>>>  - phy-reset-active-high : If present then the reset sequence using the
>GPIO
>>>>    specified in the "phy-reset-gpios" property is reversed (H=reset state,
>>>>    L=operation state).
>>>> +- phy-reset-post-delay : Post reset delay in milliseconds. If
>>>> +present then
>>>
>>> This needs unit suffix minimally. It should also have a vendor prefix
>>> or be made generic.
>>>
>>> But really, this is a property of the phy and should be in the phy
>>> node as should phy-reset-gpios, phy-reset-active-high, phy-supply, etc.
>>>
>> Yes, it is better to make it general.
>> Last year, Uwe Kleine-König's patch "Commit da47b4572056 ("phy: add
>support for a reset-gpio specification")" did this, but it was reverted by
>commit 948350140ef0 (Revert "phy: add support for a reset-gpio
>specification").  And in all phy device driver, only at803x.c add the gpio reset in
>currently.
>
>Getting the binding correct does not prevent us from later moving this reset
>code into PHYLIB where it's appropriate. In fact; a correct and generic binding
>proposed for FEC here could be used as a basis for all other MAC and PHY
>drivers.
>--
>Florian

I agree with your opinion. Just hope to add the general phy reset interface in phylib and special device driver.

Andy