Re: [PATCH] leds: tca6507: fix error handling of using fwnode_property_read_string

[Pavel Machek]

On Sun 2023-04-02 13:12:59, 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@xxxxxxxxxx>
> Cc: NeilBrown <neilb@xxxxxxx>
> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>

Acked-by: Pavel Machek <pavel@xxxxxx>

BR,							Pavel
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