linux-kernel - Re: [PATCH] net: phy: Only resume phy if it is suspended

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Message-ID: <c2ce6d12-fb5e-4067-aa7c-4f57f4eb4613@broadcom.com>
Date:   Tue, 5 Dec 2023 16:12:41 -0800
From:   Florian Fainelli <florian.fainelli@...adcom.com>
To:     Justin Chen <justin.chen@...adcom.com>,
        Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: phy: Only resume phy if it is suspended

On 12/5/23 16:10, Justin Chen wrote:
> 
> 
> On 12/5/23 4:03 PM, Andrew Lunn wrote:
>> On Tue, Dec 05, 2023 at 03:42:29PM -0800, Justin Chen wrote:
>>> Resuming the phy can take quite a bit of time. Lets only resume the
>>> phy if it is suspended.
>>
>> Humm...
>>
>> https://lore.kernel.org/netdev/6d45f4da-c45e-4d35-869f-85dd4ec37b31@lunn.ch/T/
>>
>> If Broadcom PHYs are slow to resume, maybe you should solve this in
>> the broadcom resume handler, read the status from the hardware and
>> only do the resume if the hardware is suspended.
>>
>>       Andrew
> 
> Right... Guess this won't work. It is odd that during resume we call 
> __phy_resume twice. Once from phy_resume() and another at phy_start(). 
> Let me rethink this. Thanks for the feedback.

This might be something for us to figure out on the driver side, I think 
historically I have always followed the pattern of doing:

phy_suspend()
phy_stop()

and

phy_resume()
phy_start()

because it used to be necessary to do that way back when...
-- 
Florian


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