Re: [PATCHv2 0/2] net: fec: Reset ethernet PHY whenever the enet_out clock is being enabled

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello,

On Tue, Jan 12, 2016 at 05:04:44PM +0100, Lothar Waßmann wrote:
> > On Tue, Jan 12, 2016 at 04:17:54PM +0100, Lothar Waßmann wrote:
> > > This patchset fixes a regression introduced by
> > > commit e8fcfcd5684a ("net: fec: optimize the clock management to save power")
> > > for ethernet PHYs that are using ENET_OUT as reference clock (on i.MX6 or i.MX28)
> > > 
> > > Changes vs. v1:
> > > - fixed reference to the commit that introduced the regression.
> > > - dropped patch to use gpiod framework. This should be added later,
> > >   after the affected DTBs have been updated to specify the correct
> > >   gpio_flags.
> > > 
> > > Patch overview:
> > > 1. cleanup patch to remove redundant NULL checks
> > > 2. call fec_reset_phy() after the ENET_OUT clock has been enabled
> > 
> > I definitely want to test these on my SolidRun boards before these get
> > merged: the AR8035 on there is configured via pin-straps, and then
> > further tweaked with PHY quirks.  Resetting with the iMX6 in the
> > wrong state may result in the AR8035 being reconfigured (even jumping
> > to a different MDIO address) and certainly would need the PHY quirks
> > re-running.
> > 
> As far as I can tell, all SolidRun boards do not specify the enet_out
> clock in the dtb, so the PHY reset behaviour should be unaffected by
> this patch on those boards, since the additional fec_reset_phy() call is
> framed by:
> if (fep->clk_enet_out) {
> 	...
> }
> 
> But verifying this explicitly is of course a good idea.

If the SolidRun boards don't do this, this doesn't mean it's safe in
general. The problem is real, isn't it?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |