drivers/leds/leds-lp5521.c: check if reset is successful
Make sure that the reset is successful by issuing a dummy read to R
channel current register and check its default value. On some platforms,
without this dummy read, any further access to {R/G/B}_EXEC will not have
any impact.
[akpm@linux-foundation.org: fix up code comment]
Signed-off-by: srinidhi kasagar <srinidhi.kasagar@stericsson.com>
Tested-by: Naga Radhesh <naga.radheshy@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/leds/leds-lp5521.c b/drivers/leds/leds-lp5521.c
index 16f281b..cb641f1 100644
--- a/drivers/leds/leds-lp5521.c
+++ b/drivers/leds/leds-lp5521.c
@@ -97,6 +97,9 @@
/* Status */
#define LP5521_EXT_CLK_USED 0x08
+/* default R channel current register value */
+#define LP5521_REG_R_CURR_DEFAULT 0xAF
+
struct lp5521_engine {
int id;
u8 mode;
@@ -643,6 +646,7 @@
struct lp5521_chip *chip;
struct lp5521_platform_data *pdata;
int ret, i, led;
+ u8 buf;
chip = kzalloc(sizeof(*chip), GFP_KERNEL);
if (!chip)
@@ -681,6 +685,20 @@
* Exact value is not available. 10 - 20ms
* appears to be enough for reset.
*/
+
+ /*
+ * Make sure that the chip is reset by reading back the r channel
+ * current reg. This is dummy read is required on some platforms -
+ * otherwise further access to the R G B channels in the
+ * LP5521_REG_ENABLE register will not have any effect - strange!
+ */
+ lp5521_read(client, LP5521_REG_R_CURRENT, &buf);
+ if (buf != LP5521_REG_R_CURR_DEFAULT) {
+ dev_err(&client->dev, "error in reseting chip\n");
+ goto fail2;
+ }
+ usleep_range(10000, 20000);
+
ret = lp5521_detect(client);
if (ret) {