From c1087c29e96a48e9080377e168d35dcb52fb068b Mon Sep 17 00:00:00 2001
From: "H. Nikolaus Schaller" <hns@goldelico.com>
Date: Sun, 2 Apr 2023 13:12:59 +0200
Subject: [PATCH] leds: tca6507: Fix error handling of using fwnode_property_read_string
Mime-version: 1.0
Content-type: text/plain; charset=UTF-8
Content-transfer-encoding: 8bit
Git-commit: c1087c29e96a48e9080377e168d35dcb52fb068b
Patch-mainline: v6.4-rc1
References: git-fixes
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")
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/cbae7617db83113de726fcc423a805ebaa1bfca6.1680433978.git.hns@goldelico.com
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/leds/leds-tca6507.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/leds/leds-tca6507.c
+++ b/drivers/leds/leds-tca6507.c
@@ -696,8 +696,9 @@ tca6507_led_dt_init(struct device *dev)
if (fwnode_property_read_string(child, "label", &led.name))
led.name = fwnode_get_name(child);
- fwnode_property_read_string(child, "linux,default-trigger",
- &led.default_trigger);
+ if (fwnode_property_read_string(child, "linux,default-trigger",
+ &led.default_trigger))
+ led.default_trigger = NULL;
led.flags = 0;
if (fwnode_property_match_string(child, "compatible",