On 08/09/11 23:18, Grant Grundler wrote:
> After a voltage brownout, sensor will now operate correctly.
>
> Page 10 of ISL29018 data sheet and the Intersil Application Note 1534
> describe the required initialization sequence:
> 1. Write 0x00 to register 0x08 (TEST)
> 2. Write 0x00 to register 0x00 (CMD1)
> 3. msleep(1)
> 4. program remaining registers as before
>
Nice clear comments.
> Signed-off-by: Grant Grundler <grundler@xxxxxxxxxxxx>
> Reviewed-by: Bryan Freed <bfreed@xxxxxxxxxxxx>
Acked-by: Jonathan Cameron <jic23@xxxxxxxxx>
> ---
> Change was tested on ARM/Nvidia Tegra2 (T25) machines.
> Diff below is against staging-2.6/staging-next.
> Please apply.
>
> diff --git a/drivers/staging/iio/light/isl29018.c b/drivers/staging/iio/light/isl29018.c
> index 426b6af..da5bb33 100644
> --- a/drivers/staging/iio/light/isl29018.c
> +++ b/drivers/staging/iio/light/isl29018.c
> @@ -53,6 +53,10 @@
> #define ISL29018_REG_ADD_DATA_MSB 0x03
> #define ISL29018_MAX_REGS ISL29018_REG_ADD_DATA_MSB
>
> +#define ISL29018_REG_TEST 0x08
> +#define ISL29018_TEST_SHIFT 0
> +#define ISL29018_TEST_MASK (0xFF << ISL29018_TEST_SHIFT)
> +
> struct isl29018_chip {
> struct i2c_client *client;
> struct mutex lock;
> @@ -457,6 +461,48 @@ static int isl29018_chip_init(struct i2c_client *client)
>
> memset(chip->reg_cache, 0, sizeof(chip->reg_cache));
>
> + /* Code added per Intersil Application Note 1534:
> + * When VDD sinks to approximately 1.8V or below, some of
> + * the part's registers may change their state. When VDD
> + * recovers to 2.25V (or greater), the part may thus be in an
> + * unknown mode of operation. The user can return the part to
> + * a known mode of operation either by (a) setting VDD = 0V for
> + * 1 second or more and then powering back up with a slew rate
> + * of 0.5V/ms or greater, or (b) via I2C disable all ALS/PROX
> + * conversions, clear the test registers, and then rewrite all
> + * registers to the desired values.
> + * ...
> + * FOR ISL29011, ISL29018, ISL29021, ISL29023
> + * 1. Write 0x00 to register 0x08 (TEST)
> + * 2. Write 0x00 to register 0x00 (CMD1)
> + * 3. Rewrite all registers to the desired values
> + *
> + * ISL29018 Data Sheet (FN6619.1, Feb 11, 2010) essentially says
> + * the same thing EXCEPT the data sheet asks for a 1ms delay after
> + * writing the CMD1 register.
> + */
> + status = isl29018_write_data(client, ISL29018_REG_TEST, 0,
> + ISL29018_TEST_MASK, ISL29018_TEST_SHIFT);
> + if (status < 0) {
> + dev_err(&client->dev, "Failed to clear isl29018 TEST reg."
> + "(%d)\n", status);
> + return status;
> + }
> +
> + /* See Intersil AN1534 comments above.
> + * "Operating Mode" (COMMAND1) register is reprogrammed when
> + * data is read from the device.
> + */
> + status = isl29018_write_data(client, ISL29018_REG_ADD_COMMAND1, 0,
> + 0xff, 0);
> + if (status < 0) {
> + dev_err(&client->dev, "Failed to clear isl29018 CMD1 reg."
> + "(%d)\n", status);
> + return status;
> + }
> +
> + msleep(1); /* per data sheet, page 10 */
> +
> /* set defaults */
> status = isl29018_set_range(client, chip->range, &new_range);
> if (status < 0) {
>
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