V4L/DVB (3403): Add probe check for the tda9840.

- Add probe check for the tda9840 to prevent misdetection of a Micronas
  dpl3518a as a tda9840.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/media/video/tvaudio.c b/drivers/media/video/tvaudio.c
index 6d03b9b05c6..c8e5ad0e818 100644
--- a/drivers/media/video/tvaudio.c
+++ b/drivers/media/video/tvaudio.c
@@ -390,6 +390,14 @@ static void tda9840_setmode(struct CHIPSTATE *chip, int mode)
                 chip_write(chip, TDA9840_SW, t);
 }
 
+static int tda9840_checkit(struct CHIPSTATE *chip)
+{
+        int rc;
+        rc = chip_read(chip);
+        /* lower 5 bits should be 0 */
+        return ((rc & 0x1f) == 0) ? 1 : 0;
+}
+
 /* ---------------------------------------------------------------------- */
 /* audio chip descriptions - defines+functions for tda985x                */
 
@@ -1264,6 +1272,7 @@ static struct CHIPDESC chiplist[] = {
                 .addr_hi    = I2C_TDA9840 >> 1,
                 .registers  = 5,
 
+                .checkit    = tda9840_checkit,
                 .getmode    = tda9840_getmode,
                 .setmode    = tda9840_setmode,
                 .checkmode  = generic_checkmode,