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From: Florian Fainelli <f.fainelli@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>, Sean Wang <sean.wang@mediatek.com>
Cc: sergei.shtylyov@cogentembedded.com,
	vivien.didelot@savoirfairelinux.com, davem@davemloft.net,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mediatek@lists.infradead.org, richard.leitner@skidata.com,
	geert+renesas@glider.be
Subject: Re: [net-next] phylib: Add device reset GPIO support causes DSA MT7530 acquires reset-gpios fails
Date: Mon, 18 Dec 2017 11:21:29 -0800	[thread overview]
Message-ID: <5cf08589-b4e4-3b4c-cc3e-c6100492155f@gmail.com> (raw)
In-Reply-To: <20171218080120.GD30815@lunn.ch>

On 12/18/2017 12:01 AM, Andrew Lunn wrote:
> Hi Sean
> 
>> It probably can't. Because before the GPIO line is manipulated to reset,
>> certain power control should be handled such as power sources from
>> external PMIC to let devices actually enter the proper state.
>>
>> So, I thought the kind of reset should be better controlled by the
>> specific driver, not by generic core.
> 
> Yes, the driver should do it in that case.
> 
> So we have a few choices:
> 
> 1) Change the name of one of the properties
> 
> 2) Make the new code look at the compatible string, any only apply a
>    reset if it is a PHY.
> 
> 3) Make the new code only hold the gpio when it needs it. Same for the
>    driver, so that they both can reset the device.
> 
> Any other ideas? Any preferences? 2) and 3) are probably simpler to
> do, less backwards compatibility issues. 3) potentially could cause
> issues when a device is reset in the wrong context, because of
> external PMIC etc. So i'm thinking 2).

We could also add some sort of flag that indicates whether the reset
should be managed by the core, or the driver, I would have to double
check there is not a chicken and egg problem and that the driver probe
is early enough this can happen...
-- 
Florian

  reply	other threads:[~2017-12-18 19:21 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-15  6:55 [net-next] phylib: Add device reset GPIO support causes DSA MT7530 acquires reset-gpios fails Sean Wang
2017-12-15 10:10 ` Andrew Lunn
2017-12-18  4:01   ` Sean Wang
2017-12-18  8:01     ` Andrew Lunn
2017-12-18 19:21       ` Florian Fainelli [this message]
2017-12-19  9:06 ` Sergei Shtylyov

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