drivers/leds/leds-lp5521.c: check if reset is successful (b3c49c05) · Commits · 戴 / test

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>

drivers/leds/leds-lp5521.c

+18 −0

Original line number	Diff line number	Diff line
		@@ -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) {

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