netdev - Re: [PATCH] net: phy: Add sysfs attribute to prevent PHY suspend

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Date:	Mon, 10 Mar 2014 01:53:33 +0100
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	rob@...dley.net, andrew@...n.ch, f.fainelli@...il.com,
	netdev@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: Add sysfs attribute to prevent PHY suspend

On 03/10/2014 01:41 AM, David Miller wrote:
> From: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
> Date: Mon, 10 Mar 2014 01:37:32 +0100
>
>> The mechanism is manual, no automatic way to determine it.
>
> We recognize BIOS and ACPI bugs and work around them, by looking at
> version information and whatnot, so you really can't convince me that
> something similar can't be done here perhaps in the platform code.

Hmm, if the is a way to determine the version of that particual u-boot
I'd be happy to exploit that information. But I honestly doubt that.
Compared to u-boot bootloader and kernel interaction, BIOS and ACPI
are well-defined protocols.

I personally, would prefer everybody should update his broken
bootloaders, but that will just not happen.

Anyway, at least for the two boards in question, we know a bootloader
workaround. The version does support user commands to re-enable the PHY
by writing the corresponding registers.

Unfortunately, the is a bug in phy_ethtool_get_wol that up to now,
prevents most PHYs (without .wol callbacks) from being suspended.
I wanted to get in a way to disable suspend before sending a fix.

If you are that against a sysfs knob, I guess, we will just see how
many more bootloaders are broken and some will not have a way to write
PHY registers.

Sebastian
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