media: pisp_be: Fix pm_runtime underrun in probe

During the probe() routine, the PiSP BE driver needs to power up the
interface in order to identify and initialize the hardware.

The driver resumes the interface by calling the
pispbe_runtime_resume() function directly, without going
through the pm_runtime helpers, but later suspends it by calling
pm_runtime_put_autosuspend().

This causes a PM usage count imbalance at probe time, notified by the
runtime_pm framework with the below message in the system log:

 pispbe 1000880000.pisp_be: Runtime PM usage count underflow!

Fix this by resuming the interface using the pm runtime helpers instead
of calling the resume function directly and use the pm_runtime framework
in the probe() error path. While at it, remove manual suspend of the
interface in the remove() function. The driver cannot be unloaded if in
use, so simply disable runtime pm.

To simplify the implementation, make the driver depend on PM as the
RPI5 platform where the ISP is integrated in uses the PM framework by
default.

Fixes: 12187bd ("media: raspberrypi: Add support for PiSP BE")
Cc: [email protected]
Reviewed-by: Laurent Pinchart <[email protected]>
Signed-off-by: Jacopo Mondi <[email protected]>

Author: Jacopo Mondi

drivers/media/platform/raspberrypi/pisp_be/Kconfig

@@ -2,6 +2,7 @@ config VIDEO_RASPBERRYPI_PISP_BE
 	tristate "Raspberry Pi PiSP Backend (BE) ISP driver"
 	depends on V4L_PLATFORM_DRIVERS
 	depends on VIDEO_DEV
+	depends on PM
 	depends on ARCH_BCM2835 || COMPILE_TEST
 	select VIDEO_V4L2_SUBDEV_API
 	select MEDIA_CONTROLLER

drivers/media/platform/raspberrypi/pisp_be/pisp_be.c

@@ -1774,7 +1774,7 @@ static int pispbe_probe(struct platform_device *pdev)
 	pm_runtime_use_autosuspend(pispbe->dev);
 	pm_runtime_enable(pispbe->dev);
 
-	ret = pispbe_runtime_resume(pispbe->dev);
+	ret = pm_runtime_resume_and_get(pispbe->dev);
 	if (ret)
 		goto pm_runtime_disable_err;
 
@@ -1805,7 +1805,7 @@ static int pispbe_probe(struct platform_device *pdev)
 	while (num_groups-- > 0)
 		pispbe_destroy_node_group(&pispbe->node_group[num_groups]);
 pm_runtime_suspend_err:
-	pispbe_runtime_suspend(pispbe->dev);
+	pm_runtime_put(pispbe->dev);
 pm_runtime_disable_err:
 	pm_runtime_dont_use_autosuspend(pispbe->dev);
 	pm_runtime_disable(pispbe->dev);
@@ -1820,7 +1820,6 @@ static void pispbe_remove(struct platform_device *pdev)
 	for (int i = PISPBE_NUM_NODE_GROUPS - 1; i >= 0; i--)
 		pispbe_destroy_node_group(&pispbe->node_group[i]);
 
-	pispbe_runtime_suspend(pispbe->dev);
 	pm_runtime_dont_use_autosuspend(pispbe->dev);
 	pm_runtime_disable(pispbe->dev);
 }