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From:   "Soha Jin" <soha@lohu.info>
To:     "'Greg Kroah-Hartman'" <gregkh@linuxfoundation.org>
Cc:     "'Rafael J. Wysocki'" <rafael@kernel.org>,
        "'Andy Shevchenko'" <andriy.shevchenko@linux.intel.com>,
        "'Daniel Scally'" <djrscally@gmail.com>,
        "'Heikki Krogerus'" <heikki.krogerus@linux.intel.com>,
        "'Sakari Ailus'" <sakari.ailus@linux.intel.com>,
        <linux-kernel@vger.kernel.org>
References: <20221009162155.1318-1-soha@lohu.info> <20221009162155.1318-2-soha@lohu.info> <Y0MR+uSDEm2bPgcD@kroah.com>
In-Reply-To: <Y0MR+uSDEm2bPgcD@kroah.com>
Subject: RE: [PATCH 1/3] string: add match_string_nocase() for case-insensitive match
Date:   Mon, 10 Oct 2022 11:02:39 +0800
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Hi Greg,
> On Mon, Oct 10, 2022 at 12:21:53AM +0800, Soha Jin wrote:
> > Sometimes we want to make a case-insensitive comparison with strings,
> > like checking compatible devices in fwnode properties, so this commit
> > abstracts match_string to __match_string with a compare function. The
> > original match_string will call __match_string with strcmp, and the
> > new match_string_nocase will call it with strcasecmp.
> 
> Wait, no, fwnode properties are case sensitive, why are you allowing that to
> be changed?  That sounds like broken firmware to me, right?
> 

I am writing regarding the compatibility. In `of_device_is_compatible`, it
uses `of_compat_cmp` which calls `strcasecmp` to match compatible property.

As the `fwnode_is_compatible` should be the replacement of the OF way, I
think we should make the fwnode way and the OF way the same, i.e. either
both case-insensitive or case-sensitive, to keep the consistency. I am
afraid that make `of_compat_cmp` case-sensitive may break a great many of
devices, that is why I am doing this.

Regards,
Soha