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Date:   Wed, 5 Apr 2023 16:29:08 +0100
From:   Lee Jones <lee@kernel.org>
To:     "H. Nikolaus Schaller" <hns@goldelico.com>
Cc:     Marek =?iso-8859-1?Q?Beh=FAn?= <kabel@kernel.org>,
        Pavel Machek <pavel@ucw.cz>, linux-leds@vger.kernel.org,
        linux-kernel@vger.kernel.org, letux-kernel@openphoenux.org,
        NeilBrown <neilb@suse.de>,
        Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH] leds: tca6507: fix error handling of using
 fwnode_property_read_string
Message-ID: <20230405152908.GQ8371@google.com>
References: <cbae7617db83113de726fcc423a805ebaa1bfca6.1680433978.git.hns@goldelico.com>
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On Sun, 02 Apr 2023, H. Nikolaus Schaller wrote:

> Commit 96f524105b9c ("leds: tca6507: use fwnode API instead of OF")
>
> changed to fwnode API but did not take into account that a missing property
> "linux,default-trigger" now seems to return an error and as a side effect
> sets value to -1. This seems to be different from of_get_property() which
> always returned NULL in any case of error.
>
> Neglecting this side-effect leads to
>
> [   11.201965] Unable to handle kernel paging request at virtual address ffffffff when read
>
> in the strcmp() of led_trigger_set_default() if there is no led-trigger
> defined in the DTS.
>
> I don't know if this was recently introduced somewhere in the fwnode lib
> or if the effect was missed in initial testing. Anyways it seems to be a
> bug to ignore the error return value of an optional value here in the
> driver.
>
> Fixes: 96f524105b9c ("leds: tca6507: use fwnode API instead of OF")
> Cc: Marek Behún <kabel@kernel.org>
> Cc: NeilBrown <neilb@suse.de>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
> ---
>  drivers/leds/leds-tca6507.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Applied, thanks

--
Lee Jones [李琼斯]