led: qcom-lpg: Fix sleeping in atomic

lpg_brighness_set() function can sleep, while led's brightness_set()
callback must be non-blocking. Change LPG driver to use
brightness_set_blocking() instead.

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/0
preempt_count: 101, expected: 0
INFO: lockdep is turned off.
CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W          6.1.0-rc1-00014-gbe99b089c6fc-dirty linux-sunxi#85
Hardware name: Qualcomm Technologies, Inc. DB820c (DT)
Call trace:
 dump_backtrace.part.0+0xe4/0xf0
 show_stack+0x18/0x40
 dump_stack_lvl+0x88/0xb4
 dump_stack+0x18/0x34
 __might_resched+0x170/0x254
 __might_sleep+0x48/0x9c
 __mutex_lock+0x4c/0x400
 mutex_lock_nested+0x2c/0x40
 lpg_brightness_single_set+0x40/0x90
 led_set_brightness_nosleep+0x34/0x60
 led_heartbeat_function+0x80/0x170
 call_timer_fn+0xb8/0x340
 __run_timers.part.0+0x20c/0x254
 run_timer_softirq+0x3c/0x7c
 _stext+0x14c/0x578
 ____do_softirq+0x10/0x20
 call_on_irq_stack+0x2c/0x5c
 do_softirq_own_stack+0x1c/0x30
 __irq_exit_rcu+0x164/0x170
 irq_exit_rcu+0x10/0x40
 el1_interrupt+0x38/0x50
 el1h_64_irq_handler+0x18/0x2c
 el1h_64_irq+0x64/0x68
 cpuidle_enter_state+0xc8/0x380
 cpuidle_enter+0x38/0x50
 do_idle+0x244/0x2d0
 cpu_startup_entry+0x24/0x30
 rest_init+0x128/0x1a0
 arch_post_acpi_subsys_init+0x0/0x18
 start_kernel+0x6f4/0x734
 __primary_switched+0xbc/0xc4

Fixes: 24e2d05 ("leds: Add driver for Qualcomm LPG")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

drivers/leds/rgb/leds-qcom-lpg.c

@@ -602,8 +602,8 @@ static void lpg_brightness_set(struct lpg_led *led, struct led_classdev *cdev,
 		lpg_lut_sync(lpg, lut_mask);
 }
 
-static void lpg_brightness_single_set(struct led_classdev *cdev,
-				      enum led_brightness value)
+static int lpg_brightness_single_set(struct led_classdev *cdev,
+				     enum led_brightness value)
 {
 	struct lpg_led *led = container_of(cdev, struct lpg_led, cdev);
 	struct mc_subled info;
@@ -614,10 +614,12 @@ static void lpg_brightness_single_set(struct led_classdev *cdev,
 	lpg_brightness_set(led, cdev, &info);
 
 	mutex_unlock(&led->lpg->lock);
+
+	return 0;
 }
 
-static void lpg_brightness_mc_set(struct led_classdev *cdev,
-				  enum led_brightness value)
+static int lpg_brightness_mc_set(struct led_classdev *cdev,
+				 enum led_brightness value)
 {
 	struct led_classdev_mc *mc = lcdev_to_mccdev(cdev);
 	struct lpg_led *led = container_of(mc, struct lpg_led, mcdev);
@@ -628,6 +630,8 @@ static void lpg_brightness_mc_set(struct led_classdev *cdev,
 	lpg_brightness_set(led, cdev, mc->subled_info);
 
 	mutex_unlock(&led->lpg->lock);
+
+	return 0;
 }
 
 static int lpg_blink_set(struct lpg_led *led,
@@ -1118,7 +1122,7 @@ static int lpg_add_led(struct lpg *lpg, struct device_node *np)
 		led->mcdev.num_colors = num_channels;
 
 		cdev = &led->mcdev.led_cdev;
-		cdev->brightness_set = lpg_brightness_mc_set;
+		cdev->brightness_set_blocking = lpg_brightness_mc_set;
 		cdev->blink_set = lpg_blink_mc_set;
 
 		/* Register pattern accessors only if we have a LUT block */
@@ -1132,7 +1136,7 @@ static int lpg_add_led(struct lpg *lpg, struct device_node *np)
 			return ret;
 
 		cdev = &led->cdev;
-		cdev->brightness_set = lpg_brightness_single_set;
+		cdev->brightness_set_blocking = lpg_brightness_single_set;
 		cdev->blink_set = lpg_blink_single_set;
 
 		/* Register pattern accessors only if we have a LUT block */
@@ -1151,7 +1155,7 @@ static int lpg_add_led(struct lpg *lpg, struct device_node *np)
 	else
 		cdev->brightness = LED_OFF;
 
-	cdev->brightness_set(cdev, cdev->brightness);
+	cdev->brightness_set_blocking(cdev, cdev->brightness);
 
 	init_data.fwnode = of_fwnode_handle(np);