linux-kernel - Re: [PATCH v8 0/6] Support running driver's probe for a device powered off

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Message-ID: <20200928204905.GD26842@paasikivi.fi.intel.com>
Date:   Mon, 28 Sep 2020 23:49:06 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Tomasz Figa <tfiga@...omium.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Luca Ceresoli <luca@...aceresoli.net>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Mani, Rajmohan" <rajmohan.mani@...el.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Bingbu Cao <bingbu.cao@...el.com>,
        Chiranjeevi Rapolu <chiranjeevi.rapolu@...el.com>,
        Hyungwoo Yang <hyungwoo.yang@...el.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>
Subject: Re: [PATCH v8 0/6] Support running driver's probe for a device
 powered off

Hi Tomasz,

On Mon, Sep 28, 2020 at 06:49:22PM +0200, Tomasz Figa wrote:
> On Mon, Sep 28, 2020 at 4:18 PM Rafael J. Wysocki <rafael@...nel.org> wrote:
> >
> > On Sun, Sep 27, 2020 at 9:44 PM Tomasz Figa <tfiga@...omium.org> wrote:
> > >
> > > On Sun, Sep 27, 2020 at 9:39 PM Wolfram Sang <wsa@...-dreams.de> wrote:
> > > >
> > > >
> > > > > I think we might be overly complicating things. IMHO the series as is
> > > > > with the "i2c_" prefix removed from the flags introduced would be
> > > > > reusable as is for any other subsystem that needs it. Of course, for
> > > > > now, the handling of the flag would remain implemented only in the I2C
> > > > > subsystem.
> > > >
> > > > Just to be clear: you are suggesting to remove "i2c" from the DSD
> > > > binding "i2c-allow-low-power-probe". And you are not talking about
> > > > moving I2C_DRV_FL_ALLOW_LOW_POWER_PROBE to struct device_driver? I
> > > > recall the latter has been NACKed by gkh so far.
> > > >
> > >
> > > I'd also drop "I2C_" from "I2C_DRV_FL_ALLOW_LOW_POWER_PROBE", but all
> > > the implementation would remain where it is in the code. IOW, I'm just
> > > suggesting a naming change to avoid proliferating duplicate flags of
> > > the same meaning across subsystems.
> >
> > But that would indicate that the property was recognized by other
> > subsystems which wouldn't be the case, so it would be confusing.
> >
> > That's why it cannot be documented as a general property ATM too.
> 
> I guess that's true. Well, this is kAPI in the end, so if we have more
> subsystems, it could be always renamed. So feel free to ignore my
> previous comment.

I wouldn't expect this flag to be needed outside I²C since the other
potential use case (I3C) appears to be entirely free of power management,
so it's up to the drivers on ACPI, too.

The property itself, though, might be.

-- 
Regards,

Sakari Ailus