pinctrl: st: avoid multiple mutex lock

Using the sysfs inteface to inspect the pins configuration
the system can walk around a path which acquires the same
mutex twice.

On STiH407 platform, for example :
cat /sys/kernel/debug/pinctrl/920f080.pin-controller-front0/pinconf-pins
hangs the kernel and never returns.

With this patch the mutex is temporary freed.

Signed-off-by: Francesco Virlinzi <francesco.virlinzi@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/pinctrl/pinctrl-st.c b/drivers/pinctrl/pinctrl-st.c
index 7c9d51382248..87570e68deed 100644
--- a/drivers/pinctrl/pinctrl-st.c
+++ b/drivers/pinctrl/pinctrl-st.c
@@ -1012,8 +1012,10 @@ static void st_pinconf_dbg_show(struct pinctrl_dev *pctldev,
                                    struct seq_file *s, unsigned pin_id)
 {
         unsigned long config;
-        st_pinconf_get(pctldev, pin_id, &config);
 
+        mutex_unlock(&pctldev->mutex);
+        st_pinconf_get(pctldev, pin_id, &config);
+        mutex_lock(&pctldev->mutex);
         seq_printf(s, "[OE:%ld,PU:%ld,OD:%ld]\n"
                 "\t\t[retime:%ld,invclk:%ld,clknotdat:%ld,"
                 "de:%ld,rt-clk:%ld,rt-delay:%ld]",