linux-kernel - Re: [PATCH v2 1/2] phy: add new phy_notify

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Message-ID: <yaz4ozb55t3pkwd2gj4l4d2hdspdcsqjm2dfsux7lfdxy6lxjl@uae2qz2vjo64>
Date: Wed, 23 Jul 2025 13:34:01 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Vinod Koul <vkoul@...nel.org>
Cc: Peter Griffin <peter.griffin@...aro.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, André Draszik <andre.draszik@...aro.org>, 
	Tudor Ambarus <tudor.ambarus@...aro.org>, Alim Akhtar <alim.akhtar@...sung.com>, 
	Krzysztof Kozlowski <krzk@...nel.org>, linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, kernel-team@...roid.com, 
	William Mcvicker <willmcvicker@...gle.com>
Subject: Re: [PATCH v2 1/2] phy: add new phy_notify_pmstate() api

On Wed, Jul 23, 2025 at 12:37:31PM GMT, Vinod Koul wrote:
> On 22-07-25, 22:04, Manivannan Sadhasivam wrote:
> > On Thu, Jul 03, 2025 at 02:03:22PM GMT, Peter Griffin wrote:
> > > Add a new phy_notify_pmstate() api that notifies and configures a phy for a
> > > given PM link state transition.
> > > 
> > > This is intended to be by phy drivers which need to do some runtime
> > > configuration of parameters during the transition that can't be handled by
> > > phy_calibrate() or phy_power_{on|off}().
> > > 
> > > The first usage of this API is in the Samsung UFS phy that needs to issue
> > > some register writes when entering and exiting the hibernate link state.
> > > 
> > > Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
> > > ---
> > >  drivers/phy/phy-core.c  | 25 +++++++++++++++++++++++++
> > >  include/linux/phy/phy.h | 25 +++++++++++++++++++++++++
> > >  2 files changed, 50 insertions(+)
> > > 
> > > diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> > > index 04a5a34e7a950ae94fae915673c25d476fc071c1..0b29bc2c709890d7fc27d1480a35cda6a826fd30 100644
> > > --- a/drivers/phy/phy-core.c
> > > +++ b/drivers/phy/phy-core.c
> > > @@ -520,6 +520,31 @@ int phy_notify_disconnect(struct phy *phy, int port)
> > >  }
> > >  EXPORT_SYMBOL_GPL(phy_notify_disconnect);
> > >  
> > > +/**
> > > + * phy_notify_pmstate() - phy link state notification
> > 
> > 'pmstate' doesn't correspond to 'link state'. So how about,
> > phy_notify_link_state()?
> > 
> > s/phy/PHY (here and below)
> > 
> > > + * @phy: the phy returned by phy_get()
> > > + * @state: the link state
> > > + *
> > > + * Notify the phy of some PM link state transition. Used to notify and
> > 
> > Link state change is common for the PHY. So remove 'PM'.
> 
> Is it really link or phy state?
> 

This is a bit of ambiguity. But as per the spec, Hibern8 is the low power state
of the M-PHY and Unipro controller.

Maybe, phy_notify_state()?

> > 
> > > + * configure the phy accordingly.
> > > + *
> > > + * Returns: %0 if successful, a negative error code otherwise
> > > + */
> > > +int phy_notify_pmstate(struct phy *phy, enum phy_linkstate state)
> > 
> > I think you need to use 'int state' and let drivers pass their own link state
> > values. You cannot have generic link states across all peripherals.
> 
> I would avoid that, people start overloading this if we let it keep
> open! I would like to avoid the api -(ab)use
> 

Then we will end up with peripheral specific enums in include/linux/phy/phy.h.
If you are OK with that, fine with me.

- Mani

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