netdev - Re: [PATCH net-next 2/3] net: phy: broadcom: Add support for Wake-on-LAN

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Date: Mon, 8 May 2023 12:12:01 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: netdev@...r.kernel.org, Doug Berger <opendmb@...il.com>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Heiner Kallweit <hkallweit1@...il.com>, Russell King
 <linux@...linux.org.uk>, Marek Behún <kabel@...nel.org>,
 Peter Geis <pgwipeout@...il.com>, Frank <Frank.Sae@...or-comm.com>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 2/3] net: phy: broadcom: Add support for
 Wake-on-LAN

On 5/8/23 12:09, Andrew Lunn wrote:
>> Because the Wake-on-LAN configuration can be set long before the system
>> is actually put to sleep, we cannot have an interrupt service routine to
>> clear on read the interrupt status register and ensure that new packet
>> matches will be detected.
> 
> Hi Florian
> 
> I assume the interrupt is active low, not an edge. And it will remain
> active until it is cleared? So on resume, don't you need to clear it?
> Otherwise it is already active when entering the next suspend/resume
> cycle.

The interrupt is indeed a level low driven interrupt. The interrupt is 
acknowledged by reading the WOL_INT_STATUS during bcm54xx_config_init() 
which executes during ->probe() and ->resume() and which is a clear on 
read register, this is also necessary to charge the device with the 
wake-up event.
-- 
Florian