diff options
| author | Srinidhi KASAGAR <srinidhi.kasagar@stericsson.com> | 2011-10-31 17:12:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-10-31 17:30:55 -0700 |
| commit | b3c49c05b737887443c894c66635ae68dcdf0027 (patch) | |
| tree | d2810d450aa00651620dfa160f74b6c8a066f6e4 | |
| parent | 488bc35bf40df89d37486c1826b178a2fba36ce7 (diff) | |
| download | lwn-b3c49c05b737887443c894c66635ae68dcdf0027.tar.gz lwn-b3c49c05b737887443c894c66635ae68dcdf0027.zip | |
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>
| -rw-r--r-- | drivers/leds/leds-lp5521.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/leds/leds-lp5521.c b/drivers/leds/leds-lp5521.c index 16f281b8c2d0..cb641f1b3342 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 +685,20 @@ 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 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) { |