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Subject[PATCH] drivers/leds/leds-lp5521.c: check if reset is successful
Date
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.

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>
---
drivers/leds/leds-lp5521.c | 19 +++++++++++++++++++
1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/leds/leds-lp5521.c b/drivers/leds/leds-lp5521.c
index 9fc122c..91a2928 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 @@ static int __devinit lp5521_probe(struct i2c_client *client,
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 +685,21 @@ static int __devinit lp5521_probe(struct i2c_client *client,
* Exact value is not available. 10 - 20ms
* appears to be enough for reset.
*/
+
+ /*
+ * Make sure that the chip is reset by reading back
+ * r channel current reg. This is a dummy read, otherwise
+ * in some platforms, access to R G B channel program
+ * execution mode to 'Run' in LP5521_REG_ENABLE register
+ * will not have any affect - 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) {
--
1.7.4.3


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