[PATCH 4.19 127/168] pinctrl-single: fix pcs_parse_pinconf() return value

Greg Kroah-Hartman
2020-08-17T17:40:46Z

From: Drew Fustini <drew@beagleboard.org>

[ Upstream commit f46fe79ff1b65692a65266a5bec6dbe2bf7fc70f ]

This patch causes pcs_parse_pinconf() to return -ENOTSUPP when no
pinctrl_map is added. The current behavior is to return 0 when
!PCS_HAS_PINCONF or !nconfs. Thus pcs_parse_one_pinctrl_entry()
incorrectly assumes that a map was added and sets num_maps = 2.

Analysis:
=========
The function pcs_parse_one_pinctrl_entry() calls pcs_parse_pinconf()
if PCS_HAS_PINCONF is enabled. The function pcs_parse_pinconf()
returns 0 to indicate there was no error and num_maps is then set to 2:

980 static int pcs_parse_one_pinctrl_entry(struct pcs_device *pcs,
981 struct device_node *np,
982 struct pinctrl_map **map,
983 unsigned *num_maps,
984 const char **pgnames)
985 {
<snip>
1053 (*map)->type = PIN_MAP_TYPE_MUX_GROUP;
1054 (*map)->data.mux.group = np->name;
1055 (*map)->data.mux.function = np->name;
1056
1057 if (PCS_HAS_PINCONF && function) {
1058 res = pcs_parse_pinconf(pcs, np, function, map);
1059 if (res)
1060 goto free_pingroups;
1061 *num_maps = 2;
1062 } else {
1063 *num_maps = 1;
1064 }

However, pcs_parse_pinconf() will also return 0 if !PCS_HAS_PINCONF or
!nconfs. I believe these conditions should indicate that no map was
added by returning -ENOTSUPP. Otherwise pcs_parse_one_pinctrl_entry()
will set num_maps = 2 even though no maps were successfully added, as
it does not reach "m++" on line 940:

895 static int pcs_parse_pinconf(struct pcs_device *pcs, struct device_node *np,
896 struct pcs_function *func,
897 struct pinctrl_map **map)
898
899 {
900 struct pinctrl_map *m = *map;
<snip>
917 /* If pinconf isn't supported, don't parse properties in below. */
918 if (!PCS_HAS_PINCONF)
919 return 0;
920
921 /* cacluate how much properties are supported in current node */
922 for (i = 0; i < ARRAY_SIZE(prop2); i++) {
923 if (of_find_property(np, prop2[i].name, NULL))
924 nconfs++;
925 }
926 for (i = 0; i < ARRAY_SIZE(prop4); i++) {
927 if (of_find_property(np, prop4[i].name, NULL))
928 nconfs++;
929 }
930 if (!nconfs)
919 return 0;
932
933 func->conf = devm_kcalloc(pcs->dev,
934 nconfs, sizeof(struct pcs_conf_vals),
935 GFP_KERNEL);
936 if (!func->conf)
937 return -ENOMEM;
938 func->nconfs = nconfs;
939 conf = &(func->conf[0]);
940 m++;

This situtation will cause a boot failure [0] on the BeagleBone Black
(AM3358) when am33xx_pinmux node in arch/arm/boot/dts/am33xx-l4.dtsi
has compatible = "pinconf-single" instead of "pinctrl-single".

The patch fixes this issue by returning -ENOSUPP when !PCS_HAS_PINCONF
or !nconfs, so that pcs_parse_one_pinctrl_entry() will know that no
map was added.

Logic is also added to pcs_parse_one_pinctrl_entry() to distinguish
between -ENOSUPP and other errors. In the case of -ENOSUPP, num_maps
is set to 1 as it is valid for pinconf to be enabled and a given pin
group to not any pinconf properties.

[0] https://lore.kernel.org/linux-omap/20200529175544.GA3766151@x1/

Fixes: 9dddb4df90d1 ("pinctrl: single: support generic pinconf")
Signed-off-by: Drew Fustini <drew@beagleboard.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20200608125143.GA2789203@x1
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pinctrl/pinctrl-single.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
index 7ec72ff2419a0..04a4e761e9a9c 100644
--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c
@@ -916,7 +916,7 @@ static int pcs_parse_pinconf(struct pcs_device *pcs, struct device_node *np,

/* If pinconf isn't supported, don't parse properties in below. */
if (!PCS_HAS_PINCONF)
- return 0;
+ return -ENOTSUPP;

/* cacluate how much properties are supported in current node */
for (i = 0; i < ARRAY_SIZE(prop2); i++) {
@@ -928,7 +928,7 @@ static int pcs_parse_pinconf(struct pcs_device *pcs, struct device_node *np,
nconfs++;
}
if (!nconfs)
- return 0;
+ return -ENOTSUPP;

func->conf = devm_kcalloc(pcs->dev,
nconfs, sizeof(struct pcs_conf_vals),
@@ -1056,9 +1056,12 @@ static int pcs_parse_one_pinctrl_entry(struct pcs_device *pcs,

if (PCS_HAS_PINCONF && function) {
res = pcs_parse_pinconf(pcs, np, function, map);
- if (res)
+ if (res == 0)
+ *num_maps = 2;
+ else if (res == -ENOTSUPP)
+ *num_maps = 1;
+ else
goto free_pingroups;
- *num_maps = 2;
} else {
*num_maps = 1;
}
--
2.25.1