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drivers/leds/leds-lp5521.c: check if reset is successful

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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>
This commit is contained in:
Srinidhi KASAGAR 2011-10-31 17:12:24 -07:00 committed by Linus Torvalds
parent 488bc35bf4
commit b3c49c05b7
1 changed files with 18 additions and 0 deletions
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18
drivers/leds/leds-lp5521.c
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@ -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) {