netdev - Re: [PATCH v2 1/2] ARM: imx6: disable deeper idle states when FEC is active w/o HW workaround

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Message-ID: <1465464924.18807.5.camel@pengutronix.de>
Date:	Thu, 09 Jun 2016 11:35:24 +0200
From:	Lucas Stach <l.stach@...gutronix.de>
To:	Fugang Duan <fugang.duan@....com>, Shawn Guo <shawnguo@...nel.org>
Cc:	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"patchwork-lst@...gutronix.de" <patchwork-lst@...gutronix.de>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] ARM: imx6: disable deeper idle states when FEC
 is active w/o HW workaround

Hi Fugang,

Am Montag, den 06.06.2016, 02:00 +0000 schrieb Fugang Duan:
> From: Lucas Stach <l.stach@...gutronix.de> Sent: Saturday, June 04,
> 2016 12:31 AM
> > 
> > To: Shawn Guo <shawnguo@...nel.org>; Fugang Duan <fugang.duan@....c
> > om>
> > Cc: devicetree@...r.kernel.org; patchwork-lst@...gutronix.de;
> > kernel@...gutronix.de; linux-arm-kernel@...ts.infradead.org;
> > netdev@...r.kernel.org
> > Subject: [PATCH v2 1/2] ARM: imx6: disable deeper idle states when
> > FEC is
> > active w/o HW workaround
> > 
> > The i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC
> > from waking
> > the CPUs when they are in wait(unclocked) state. As the hardware
> > workaround
> > isn't applicable to all boards, disable the deeper idle state when
> > the workaround
> > isn't present and the FEC is in use.
> > 
> > This allows to safely run a kernel with CPUidle enabled on all
> > i.MX6 boards.
> > 
> > Signed-off-by: Lucas Stach <l.stach@...gutronix.de>
> > Acked-by: David S. Miller <davem@...emloft.net> (for network
> > changes)
> > ---

[...]

> Hi, Lucas,
> 
> FEC irq cannot wake up CPUs when system is in wait mode. But we can
> use GPIO_6 for FEC interrupt that GPIO irq wake up CPUs.
> No need to disable wait mode as your such patches.
> 
> You just config the gpio irq like below patches:
> bc20a5d6da71 (ARM: dts: imx6qdl-sabreauto: use GPIO_6 for FEC
> interrupt.)
> 6261c4c8f13e (ARM: dts: imx6qdl-sabrelite: use GPIO_6 for FEC
> interrupt.)
> 
Please look at the description of this series again. The changes don't
disable the deeper idle states on boards where the HW waorkaround is
available. There is a large number of boards in the wild which can not
use the HW workaround, as they use GPIO_6 for other purposes. The aim
of this series is to have an automatic software workaround available
for those boards.

Regards,
Lucas