netdev - Re: [PATCH v6 1/6] net: phy: at803x: Export at803x_debug_reg

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Message-ID: <20180511183850.tjzj4urhiiqfjtfq@pburton-laptop>
Date:   Fri, 11 May 2018 11:38:51 -0700
From:   Paul Burton <paul.burton@...s.com>
To:     Andrew Lunn <andrew@...n.ch>, Darren Hart <dvhart@...radead.org>
CC:     <netdev@...r.kernel.org>, <linux-mips@...ux-mips.org>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH v6 1/6] net: phy: at803x: Export at803x_debug_reg_mask()

On Fri, May 11, 2018 at 11:25:02AM -0700, Paul Burton wrote:
> Hi Andrew,
> 
> On Fri, May 11, 2018 at 02:26:19AM +0200, Andrew Lunn wrote:
> > On Thu, May 10, 2018 at 04:16:52PM -0700, Paul Burton wrote:
> > > From: Andrew Lunn <andrew@...n.ch>
> > > 
> > > On some boards, this PHY has a problem when it hibernates. Export this
> > > function to a board can register a PHY fixup to disable hibernation.
> > 
> > What do you know about the problem?
> > 
> > https://patchwork.ozlabs.org/patch/686371/
> > 
> > I don't remember how it was solved, but you should probably do the
> > same.
> > 
> > 	Andrew
> 
> I'm afraid I don't know much about the problem - this one is your patch
> entirely unchanged, and I don't have access to the hardware in question
> (my board uses a Realtek RTL8211E PHY).
> 
> I presume you did this because the pch_gbe driver as-is in mainline
> disables hibernation for the AR803X PHY found on the MinnowBoard, so
> this would be preserving the existing behaviour of the driver?
> 
> That behaviour was introduced by commit f1a26fdf5944f ("pch_gbe: Add
> MinnowBoard support"), so perhaps Darren as its author might know more?
> 
> My presumption would be that this is done to ensure that the PHY is
> always providing the RX clock, which the EG20T manual says is required
> for the MAC reset register RX_RST & ALL_RST bits to clear. We wait for
> those using the call to pch_gbe_wait_clr_bit() in
> pch_gbe_mac_reset_hw(), which happens before we initialize the PHY.
> 
> I could reorder the probe function a little to initialize the PHY before
> performing the MAC reset, drop this patch and the AR803X hibernation
> stuff from patch 2 if you like. But again, I can't actually test the
> result on the affected hardware.
> 
> Thanks,
>     Paul

I got an undeliverable response using Darren's email address from the
commit referenced above, so updating to the latest address I see for him
in git history.

Thanks,
    Paul