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Date: Mon, 29 Apr 2024 11:54:29 +0300
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= <u.kleine-koenig@pengutronix.de>
Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Krzysztof Kozlowski <krzk@kernel.org>, linux-i2c@vger.kernel.org,
	linux-kernel@vger.kernel.org, kernel@pengutronix.de
Subject: Re: [PATCH RFC] i2c: Add a void pointer to i2c_device_id
Message-ID: <Zi9gRVVw7qbKSL5k@smile.fi.intel.com>
References: <20240426213832.915485-2-u.kleine-koenig@pengutronix.de>
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On Fri, Apr 26, 2024 at 11:38:33PM +0200, Uwe Kleine-K?nig wrote:
> Traditionally a struct i2c_device_id has a kernel_ulong_t member to
> store some chip variant data. Some drivers use it to store an enum,
> others to store a pointer. In the latter case there is some ugly(?)
> casting involved. To improve that, add a void pointer in an anonymous
> union together with the integer driver_data.
> 
> This way a i2c_device_id requires usage of a designated initializer when
> the driver_data or data member should be initialized, but IMHO that's
> fine and you might even consider that an advantage.

..

>  static const struct i2c_device_id wlf_gf_module_id[] = {
> -	{ "wlf-gf-module", 0 },
> +	{ "wlf-gf-module", },

In such cases the inner comma is redundant as well.

>  	{ }
>  };

..

In general idea might be okay, but I always have the same Q (do we have it
being clarified in the documentation, btw): is an ID table the ABI or not?
In another word, how should we treat the changes there, because ID tables
are being used by the user space tools.

-- 
With Best Regards,
Andy Shevchenko