Re: [PATCH] net: phy: micrel: reconfigure the phy on resume

On 11.02.2021 13:17, Pavel Machek wrote:

On Thu 2021-01-14 12:05:21, Heiner Kallweit wrote:

quoted

On 14.01.2021 11:41, Claudiu.Beznea@microchip.com wrote:

quoted

On 14.01.2021 12:25, Russell King - ARM Linux admin wrote:

quoted

As I've said, if phylib/PHY driver is not restoring the state of the
PHY on resume from suspend-to-ram, then that's an issue with phylib
and/or the phy driver.

In the patch I proposed in this thread the restoring is done in PHY driver.
Do you think I should continue the investigation and check if something
should be done from the phylib itself?

It was the right move to approach the PM maintainers to clarify whether
the resume PM callback has to assume that power had been cut off and
it has to completely reconfigure the device. If they confirm this
understanding, then:

Power to some devices can be cut during s2ram, yes.

Thanks for the confirmation.

quoted

- the general question remains why there's separate resume and restore
  callbacks, and what restore is supposed to do that resume doesn't
  have to do

You'll often have same implementation, yes.

If resume and restore both have to assume that power was cut off,
then they have to fully re-initialize the device. Therefore it's still
not clear to me when you would have differing implementations for both
callbacks.

quoted

- it should be sufficient to use mdio_bus_phy_restore also as resume
  callback (instead of changing each and every PHY driver's resume),
  because we can expect that somebody cutting off power to the PHY
  properly suspends the MDIO bus before

If restore works with power cut and power not cut then yes, you should
get away with that.

Best regards,
								Pavel

Heiner