netdev - Re: [EXT] Prestera driver fail to probe twice

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Date: Wed, 7 Feb 2024 12:28:38 +0100
From: Köry Maincent <kory.maincent@...tlin.com>
To: Elad Nachman <enachman@...vell.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, Taras Chornyi
 <taras.chornyi@...ision.eu>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>, Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [EXT] Prestera driver fail to probe twice

On Wed, 7 Feb 2024 10:56:29 +0000
Elad Nachman <enachman@...vell.com> wrote:

> > -----Original Message-----
> > From: Köry Maincent <kory.maincent@...tlin.com>
> > Sent: Wednesday, February 7, 2024 12:23 PM
> > To: Elad Nachman <enachman@...vell.com>
> > Cc: netdev@...r.kernel.org; Taras Chornyi <taras.chornyi@...ision.eu>;
> > Thomas Petazzoni <thomas.petazzoni@...tlin.com>; Miquel Raynal
> > <miquel.raynal@...tlin.com>
> > Subject: Re: [EXT] Prestera driver fail to probe twice
> > 
> > On Tue, 6 Feb 2024 18:30:33 +0000
> > Elad Nachman <enachman@...vell.com> wrote:
> >   
> > > Sorry, that's not how this works.
> > >
> > > The firmware CPU loader will only reload if the firmware crashed or exit.
> > >
> > > Hence, insmod on the host side will fail, as the firmware side loader
> > > is not waiting For the host to send a new firmware, but first for the
> > > existing firmware to exit.  
> > 
> > With the current implementation we can't rmmod/insmod the driver.
> > Also, in case of deferring probe the same problem appears and the driver
> > will never probe. I don't think this is a good behavior.
> > 
> > Isn't it possible to verify that the firmware has already been sent and is
> > working well at the probe time? Then we wouldn't try to flash it.  
> 
> Everything is possible, but that is the way the firmware interface was
> initially designed. Changing this will break compatibility with board already
> deployed in the field.

I don't understand, why fixing the probe by not flashing the firmware if it is
already flashed, will break compatibility?
Do I miss something?

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com