netdev - Re: [PATCH net-next 3/4] net: phy-c45: Implement reset/suspend/resume callbacks

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Message-ID: <20181023102023.GM30658@n2100.armlinux.org.uk>
Date:   Tue, 23 Oct 2018 11:20:24 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Jose Abreu <jose.abreu@...opsys.com>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Joao Pinto <joao.pinto@...opsys.com>
Subject: Re: [PATCH net-next 3/4] net: phy-c45: Implement
 reset/suspend/resume callbacks

On Tue, Oct 23, 2018 at 11:17:50AM +0100, Jose Abreu wrote:
> On 22-10-2018 18:13, Florian Fainelli wrote:
> > On 10/22/18 8:48 AM, Russell King - ARM Linux wrote:
> >> On Mon, Oct 22, 2018 at 01:47:48PM +0100, Jose Abreu wrote:
> >>> Hello,
> >>>
> >>> On 22-10-2018 13:28, Andrew Lunn wrote:
> >>>>>  EXPORT_SYMBOL_GPL(gen10g_resume);
> >>>>> @@ -327,7 +381,7 @@ struct phy_driver genphy_10g_driver = {
> >>>>>  	.phy_id         = 0xffffffff,
> >>>>>  	.phy_id_mask    = 0xffffffff,
> >>>>>  	.name           = "Generic 10G PHY",
> >>>>> -	.soft_reset	= gen10g_no_soft_reset,
> >>>>> +	.soft_reset	= gen10g_soft_reset,
> >>>>>  	.config_init    = gen10g_config_init,
> >>>>>  	.features       = 0,
> >>>>>  	.aneg_done	= genphy_c45_aneg_done,
> >>>> Hi Jose
> >>>>
> >>>> You need to be careful here. There is a reason this is called
> >>>> gen10g_no_soft_reset, rather than having an empty
> >>>> gen10g_soft_reset. Some PHYs break when you do a reset.  So adding a
> >>>> gen10g_soft_reset is fine, but don't change this here, without first
> >>>> understanding the history, and talking to Russell King.
> >>> Hmm, the reset function only interacts with standard PCS
> >>> registers, which should always be available ...
> >>>
> >>> >From my tests I need to do at least 1 reset during power-up so in
> >>> ultimate case I can add a feature quirk or similar.
> >>>
> >>> Russell, can you please comment ?
> >> Setting the reset bit on 88x3310 causes the entire device to become
> >> completely inaccessible until hardware reset.  Therefore, this bit
> >> must _never_ be set for these devices.  That said, we have a separate
> >> driver for these PHYs, but that will only be used for them if it's
> >> present in the kernel.  If we accidentally fall back to the generic
> >> driver, then we'll screw the 88x3310 until a full hardware reset.
> >>
> >> We also have a bunch of net devices that make use of this crippled
> >> "generic" 10G support - we don't know whether resetting the PHY
> >> for those systems will cause a regression - maybe board firmware
> >> already configured the PHY?  I can't say either way on that, except
> >> that we've had crippled 10G support in PHYLIB for a number of years
> >> now _with_ users, and adding reset support drastically changes the
> >> subsystem's behaviour for these users.
> >>
> >> I would recommend not touching the generic 10G driver, but instead
> >> implement your own driver for your PHY to avoid causing regressions.
> >>
> > Agreed.
> 
> What about .suspend / .resume ?

I have no idea what you're proposing there - your patches weren't copied
to me.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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