Re: [PATCH RFC v1 7/7] net: cpsw: resume/suspend PHY on port start/stop

[Sebastian Hesselbarth]

On 11/20/2013 09:48 PM, Florian Fainelli wrote:
> 2013/11/20 Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>:
> > Network PHYs consume a noticable amount of power. This adds phy_resume
> > on slave_open and phy_suspend on slave_stop to save this power if the
> > port is down anyway.
> >
> > Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
> > ---
> > Cc: David S. Miller <davem@xxxxxxxxxxxxx>
> > Cc: netdev@xxxxxxxxxxxxxxx
> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > ---
> >   drivers/net/ethernet/ti/cpsw.c |    2 ++
> >   1 files changed, 2 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
> > index 90d41d2..f1dc54f 100644
> > --- a/drivers/net/ethernet/ti/cpsw.c
> > +++ b/drivers/net/ethernet/ti/cpsw.c
> > @@ -1013,6 +1013,7 @@ static void cpsw_slave_open(struct cpsw_slave *slave, struct cpsw_priv *priv)
> >          } else {
> >                  dev_info(priv->dev, "phy found : id is : 0x%x\n",
> >                           slave->phy->phy_id);
> > +               phy_resume(slave->phy);
> >                  phy_start(slave->phy);
>
> Cannot phy_start() figure this out for us based on the internal PHY
> device state machine?

Yeah, as I said in the cover letter, I started with mv643xx_eth which
is not using phy_start/stop as it probably should be. As soon as I
looked at mvneta/cpsw, I also came to the conclusion that
phy_suspend/resume should be hidden in phy_start/stop.

> I would imagine that you would want to call phy_suspend/resume from an
> Ethernet driver's PM suspend/resume callbacks to make sure that the
> PHY also enters a low power mode, but I do not want to have to
> remember that I need to call phy_resume before phy_start for instance.
> As of today we have PHY_HALTED/PHY_RESUMING, and I think we certainly
> need at least a PHY_SUSPENDED state to help us with that.
>
> >                  /* Configure GMII_SEL register */
> > @@ -1081,6 +1082,7 @@ static void cpsw_slave_stop(struct cpsw_slave *slave, struct cpsw_priv *priv)
> >          if (!slave->phy)
> >                  return;
> >          phy_stop(slave->phy);
> > +       phy_suspend(slave->phy);
>
> Same here, why is not that hidden in phy_stop? If there is any fear
> that this breaks setups where WoL is used or such, we could add a new
> argument to phy_connect() and friends which says whether it is okay to
> auto-suspend the PHY upon PHY_stop
>
> >          phy_disconnect(slave->phy);
> >          slave->phy = NULL;
> >   }
> > --
> > 1.7.2.5
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/