From: Francesco VIRLINZI <francesco.virli...@st.com>

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.virli...@st.com>
Signed-off-by: Patrice Chotard <patrice.chot...@st.com>
---
 drivers/pinctrl/pinctrl-st.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/pinctrl-st.c b/drivers/pinctrl/pinctrl-st.c
index caeeb1c..2870a68 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]",
-- 
1.9.1

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