[PATCH v4] media: bcm2835-unicam: Fix log status runtime access

When requesting log status, the block might be powered off, but registers
are being read.
Avoid reading the registers if the device is not resumed, thus also avoid
powering up the device just for log status.

Fixes: 392cd78d495f ("media: bcm2835-unicam: Add support for CCP2/CSI2 camera interface")
Signed-off-by: Eugen Hristev <[email protected]>
---
Changes in v4:
- rebased on latest tree, no additional change.
- Link to v3: https://patch.msgid.link/[email protected]

Changes in v3:
- Changed to check return value of pm_runtime_get_if_active() and only call
  pm_runtime_put() if the device is active.
- Link to v2: https://patch.msgid.link/[email protected]

Changes in v2:
- changed to use pm_runtime_get_if_active()
- add corresponding put()
- Link to v1: https://patch.msgid.link/[email protected]

To: Raspberry Pi Kernel Maintenance <[email protected]>
To: Mauro Carvalho Chehab <[email protected]>
To: Florian Fainelli <[email protected]>
To: Ray Jui <[email protected]>
To: Scott Branden <[email protected]>
To: Broadcom internal kernel review list <[email protected]>
To: Sakari Ailus <[email protected]>
To: Jean-Michel Hautbois <[email protected]>
To: Laurent Pinchart <[email protected]>
To: Hans Verkuil <[email protected]>
To: Naushir Patuck <[email protected]>
Cc: Dave Stevenson <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
 drivers/media/platform/broadcom/bcm2835-unicam.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/media/platform/broadcom/bcm2835-unicam.c b/drivers/media/platform/broadcom/bcm2835-unicam.c
index 14bb916dd7b1..7745aee711cb 100644
--- a/drivers/media/platform/broadcom/bcm2835-unicam.c
+++ b/drivers/media/platform/broadcom/bcm2835-unicam.c
@@ -2043,6 +2043,7 @@ static int unicam_log_status(struct file *file, void *fh)
 	struct unicam_node *node = video_drvdata(file);
 	struct unicam_device *unicam = node->dev;
 	u32 reg;
+	int pm_active;
 
 	/* status for sub devices */
 	v4l2_device_call_all(&unicam->v4l2_dev, 0, core, log_status);
@@ -2052,6 +2053,14 @@ static int unicam_log_status(struct file *file, void *fh)
 		 node->fmt.fmt.pix.width, node->fmt.fmt.pix.height);
 	dev_info(unicam->dev, "V4L2 format:         %08x\n",
 		 node->fmt.fmt.pix.pixelformat);
+
+	pm_active = pm_runtime_get_if_active(unicam->dev);
+	if (!pm_active) {
+		dev_info(unicam->dev,
+			 "Live data N/A due to device inactive\n");
+		return 0;
+	}
+
 	reg = unicam_reg_read(unicam, UNICAM_IPIPE);
 	dev_info(unicam->dev, "Unpacking/packing:   %u / %u\n",
 		 unicam_get_field(reg, UNICAM_PUM_MASK),
@@ -2065,6 +2074,9 @@ static int unicam_log_status(struct file *file, void *fh)
 	dev_info(unicam->dev, "Write pointer:       %08x\n",
 		 unicam_reg_read(unicam, UNICAM_IBWP));
 
+	if (pm_active == 1)
+		pm_runtime_put(unicam->dev);
+
 	return 0;
 }
 

---
base-commit: 903c1cf6dff9964e71eda98a39e2e5d442050472
change-id: 20260521-bcmpipm-6c578e73239c

Best regards,
--  
Eugen Hristev <[email protected]>