media: bcm2835-unicam: Return early from stop_streaming() if stopped

clk_disable_unprepare() is called unconditionally in stop_streaming().
This is incorrect in the cases where start_streaming() fails, and
unprepares all clocks as part of the failure cleanup. To avoid this,
ensure that clk_disable_unprepare() is only called in stop_streaming()
if the clocks are in a prepared state.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>

diff --git a/drivers/media/platform/bcm2835/bcm2835-unicam.c b/drivers/media/platform/bcm2835/bcm2835-unicam.c
index c13a0a2..60309de 100644 (file)
--- a/drivers/media/platform/bcm2835/bcm2835-unicam.c
+++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c
@@ -426,6 +426,8 @@ struct unicam_device {
        struct clk *clock;
        /* vpu clock handle */
        struct clk *vpu_clock;
+       /* clock status for error handling */
+       bool clocks_enabled;
        /* V4l2 device */
        struct v4l2_device v4l2_dev;
        struct media_device mdev;
@@ -1724,6 +1726,7 @@ static int unicam_start_streaming(struct vb2_queue *vq, unsigned int count)
                goto err_disable_unicam;
        }
 
+       dev->clocks_enabled = true;
        return 0;
 
 err_disable_unicam:
@@ -1750,8 +1753,6 @@ static void unicam_stop_streaming(struct vb2_queue *vq)
        node->streaming = false;
 
        if (node->pad_id == IMAGE_PAD) {
-               int ret;
-
                /*
                 * Stop streaming the sensor and disable the peripheral.
                 * We cannot continue streaming embedded data with the
@@ -1762,12 +1763,13 @@ static void unicam_stop_streaming(struct vb2_queue *vq)
 
                unicam_disable(dev);
 
-               ret = clk_set_min_rate(dev->vpu_clock, 0);
-               if (ret)
-                       unicam_err(dev, "failed to reset the min VPU clock\n");
+               if (dev->clocks_enabled) {
+                       if (clk_set_min_rate(dev->vpu_clock, 0))
+                               unicam_err(dev, "failed to reset the min VPU clock\n");
 
-               clk_disable_unprepare(dev->vpu_clock);
-               clk_disable_unprepare(dev->clock);
+                       clk_disable_unprepare(dev->vpu_clock);
+                       clk_disable_unprepare(dev->clock);
+               }
                unicam_runtime_put(dev);
 
        } else if (node->pad_id == METADATA_PAD) {