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authorLinus Walleij <linus.walleij@linaro.org>2016-11-12 17:01:09 +0300
committerLinus Walleij <linus.walleij@linaro.org>2016-11-15 12:26:34 +0300
commit60f8339eb388df8a46f8eb4282ff0e15f08f218c (patch)
treeb6945de6817572f75673024744bd19aeda41c184 /drivers/gpio
parent386377b5473043c09b2de40bfe5abfb0fc87e1b4 (diff)
downloadlinux-60f8339eb388df8a46f8eb4282ff0e15f08f218c.tar.xz
gpio: do not double-check direction on sleeping chips
When locking a GPIO line as IRQ, we go to lengths to double-check that the line is really set as input before marking it as used for IRQ. This is not good on GPIO chips that can sleep, because this function is called in IRQ-safe context. Just skip this if it can't be checked quickly. Currently this happens on sleeping expanders such as STMPE or TC3589x: BUG: scheduling while atomic: swapper/1/0x00000002 Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.0-rc1+ #38 Hardware name: Nomadik STn8815 [<c000f2e0>] (unwind_backtrace) from [<c000d244>] (show_stack+0x10/0x14) [<c000d244>] (show_stack) from [<c0037b78>] (__schedule_bug+0x54/0x80) [<c0037b78>] (__schedule_bug) from [<c042df14>] (__schedule+0x3a0/0x460) [<c042df14>] (__schedule) from [<c042e028>] (schedule+0x54/0xb8) (...) This patch fixes that problem and relies on the direction read from the chip when it was added. Cc: stable@vger.kernel.org Fixes: 9c10280d85c1 ("gpio: flush direction status in gpiochip_lock_as_irq()") Cc: Patrice Chotard <patrice.chotard@st.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpiolib.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 93ed0e00c578..868128a676ba 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2737,8 +2737,11 @@ int gpiochip_lock_as_irq(struct gpio_chip *chip, unsigned int offset)
if (IS_ERR(desc))
return PTR_ERR(desc);
- /* Flush direction if something changed behind our back */
- if (chip->get_direction) {
+ /*
+ * If it's fast: flush the direction setting if something changed
+ * behind our back
+ */
+ if (!chip->can_sleep && chip->get_direction) {
int dir = chip->get_direction(chip, offset);
if (dir)