backlight: add more information output to pwm_backlight

Make the error paths in the pwm_backlight driver more informative in the
probe path, especially for the times that it finds an error.

Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 6338d0e2fe07..441e5a707d37 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -68,8 +68,10 @@ static int pwm_backlight_probe(struct platform_device *pdev)
         struct pwm_bl_data *pb;
         int ret;
 
-        if (!data)
+        if (!data) {
+                dev_err(&pdev->dev, "failed to find platform data\n");
                 return -EINVAL;
+        }
 
         if (data->init) {
                 ret = data->init(&pdev->dev);
@@ -79,6 +81,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 
         pb = kzalloc(sizeof(*pb), GFP_KERNEL);
         if (!pb) {
+                dev_err(&pdev->dev, "no memory for state\n");
                 ret = -ENOMEM;
                 goto err_alloc;
         }
@@ -91,7 +94,8 @@ static int pwm_backlight_probe(struct platform_device *pdev)
                 dev_err(&pdev->dev, "unable to request PWM for backlight\n");
                 ret = PTR_ERR(pb->pwm);
                 goto err_pwm;
-        }
+        } else
+                dev_dbg(&pdev->dev, "got pwm for backlight\n");
 
         bl = backlight_device_register(pdev->name, &pdev->dev,
                         pb, &pwm_backlight_ops);