Hi Jacopo and Co,
Jacopo Mondi <jacopo@xxxxxxxxxx> writes:
> +static int ar0521_read_reg(struct ar0521_dev *sensor, u16 reg, u16 *val)
> +{
> + struct i2c_client *client = sensor->i2c_client;
> + unsigned char buf[2];
> + struct i2c_msg msg;
> + int ret;
> +
> + msg.addr = client->addr;
> + msg.flags = client->flags;
> + msg.len = sizeof(u16);
> + msg.buf = buf;
> + put_unaligned_be16(reg, buf);
> +
> + ret = i2c_transfer(client->adapter, &msg, 1);
> + if (ret < 0)
> + return ret;
> +
> + msg.len = sizeof(u16);
> + msg.flags = client->flags | I2C_M_RD;
> + msg.buf = buf;
> +
> + ret = i2c_transfer(client->adapter, &msg, 1);
> + if (ret < 0)
> + return ret;
> +
> + *val = get_unaligned_be16(buf);
> +
> + return 0;
> +}
Why not simply use a shadow register?
> +static int ar0521_set_analog_gain(struct ar0521_dev *sensor)
> +{
> + u16 global_gain;
> + int ret;
> +
> + ret = ar0521_read_reg(sensor, AR0521_REG_GLOBAL_GAIN, &global_gain);
> + if (ret)
> + return ret;
> +
> + global_gain &= ~AR0521_REG_GLOBAL_GAIN_ANA_MASK;
> + global_gain |= sensor->ctrls.ana_gain->val & AR0521_REG_GLOBAL_GAIN_ANA_MASK;
> +
> + return ar0521_write_reg(sensor, AR0521_REG_GLOBAL_GAIN, global_gain);
This one is simple: you can't write to AR0521_REG_GLOBAL_GAIN.
You can write to individual color gain registers (any will do for analog
gain), but writing to AR0521_REG_GLOBAL_GAIN will reset all the digital
gains as well. Reading the register doesn't give you anything
interesting, either (the analog gain which you overwrite anyway).
BTW ISP can't really do that color balancing for you, since the sensor
operates at its native bit resolution and ISP is limited to the output
format, which is currently only 8-bit.
--
Krzysztof "Chris" Hałasa
Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa
