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

[Lucas Stach <l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

Hi Fugang,

Am Montag, den 06.06.2016, 02:00 +0000 schrieb Fugang Duan:
> From: Lucas Stach <l.stach-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sent: Saturday, June 04,
> 2016 12:31 AM
> > 
> > To: Shawn Guo <shawnguo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>; Fugang Duan <fugang.duan@nxp.c
> > om>
> > Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; patchwork-lst-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org;
> > kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org; linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org;
> > netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.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-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> > Acked-by: David S. Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org> (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
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