linux-kernel - RE: [PATCH v7 0/4] Extend device_get_match_data() to struct bus

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Date:   Tue, 15 Aug 2023 07:06:35 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Jonathan Cameron <jic23@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Peter Rosin <peda@...ntia.se>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        Andi Shyti <andi.shyti@...nel.org>,
        Wolfram Sang <wsa@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH v7 0/4] Extend device_get_match_data() to struct bus_type

> Subject: RE: [PATCH v7 0/4] Extend device_get_match_data() to struct
> bus_type
> 
> 
> Hi Andy Shevchenko,
> 
> Thanks for the feedback.
> 
> > Subject: Re: [PATCH v7 0/4] Extend device_get_match_data() to struct
> > bus_type
> >
> > On Fri, Aug 11, 2023 at 02:46:10PM +0000, Biju Das wrote:
> > > > Subject: Re: [PATCH v7 0/4] Extend device_get_match_data() to
> > > > struct bus_type On Fri, Aug 11, 2023 at 01:27:36PM +0000, Biju Das
> wrote:
> > > > > > On Thu, Aug 10, 2023 at 09:05:10AM +0000, Biju Das wrote:
> >
> > ...
> >
> > > > > > I'm good with this approach, but make sure you checked the
> > > > > > whole kernel source tree for a such.
> > > > >
> > > > > Checking against 16 is too short I guess??
> > > > >
> > > > > drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h has 18 enums.
> > > >
> > > > So, what does prevent us from moving that tables to use pointers?
> > >
> > > I think that will lead to ABI breakage(client->name vs id->name)
> > >
> > > 	match = device_get_match_data(&client->dev);
> > > 	if (match) {
> > > 		chip_type = (uintptr_t)match;
> > > 		name = client->name;
> > > 	} else if (id) {
> > > 		chip_type = (enum inv_devices)
> > > 			id->driver_data;
> > > 		name = id->name;
> > > 	} else {
> > > 		return -ENOSYS;
> > > 	}
> >
> >
> > It's easy to work around (may be better fix can be found, haven't
> > checked, just what first comes to my mind):
> >
> > 	match ...
> > 	name = match->name;
> 
> The device_get_match_data()API returns matched data, so we cannot use that
> one here.
> 
> Maybe??
> 
> /* If enumerated via ID lookup, fix the ABI */ if (!dev_fwnode())
> 	name = id->name;

Looks this will work.

/* If enumerated via firmware node, fix the ABI */
	if (dev_fwnode())
		name = client->name
	else
		name = id->name

Cheers,
Biju