On 06/18/2015 05:17 PM, Simon Guinot wrote:
On the board n090401 (Seagate NAS 4-Bay), some of the LEDs are handled
by the leds-ns2 driver. This LEDs are connected to an I2C GPIO expander
(PCA95554PW) which means that GPIO access may sleep. This patch makes
leds-ns2 compatible with such GPIOs by using the *_cansleep() variant of
the GPIO functions. As a drawback this functions can't be used safely in
a timer context (with the timer LED trigger for example). To fix this
issue, a workqueue mechanism (copied from the leds-gpio driver) is used.
Note that this patch also updates slightly the ns2_led_sata_store
function. The LED state is now retrieved from cached values instead of
reading the GPIOs previously. This prevents ns2_led_sata_store from
working with a stale LED state (which may happen when a delayed work
is pending).
Signed-off-by: Simon Guinot <[email protected]>
Signed-off-by: Vincent Donnefort <[email protected]>
---
drivers/leds/leds-ns2.c | 56 ++++++++++++++++++++++++++++++++++++-------------
1 file changed, 42 insertions(+), 14 deletions(-)
+static void ns2_led_work(struct work_struct *work)
+{
+ struct ns2_led_data *led_dat =
+ container_of(work, struct ns2_led_data, work);
+ int i = led_dat->new_mode_index;
+
+ write_lock(&led_dat->rw_lock);
+
+ gpio_set_value_cansleep(led_dat->cmd, led_dat->modval[i].cmd_level);
+ gpio_set_value_cansleep(led_dat->slow, led_dat->modval[i].slow_level);
+
+ write_unlock(&led_dat->rw_lock);
+}
+
I've just realized that this can break one of the basic rules:
no sleeping should occur while holding a spinlock. Did you
consider this?
--
Best Regards,
Jacek Anaszewski
--
To unsubscribe from this list: send the line "unsubscribe linux-leds" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
