Re: [V3, 2/2] media: i2c: Add DW9768 VCM driver

Andy Shevchenko
2020-03-02T11:07:32Z

On Fri, Feb 28, 2020 at 11:59:58PM +0800, Dongchun Zhu wrote:
> This patch adds a V4L2 sub-device driver for DW9768 lens voice coil,
> and provides control to set the desired focus via I2C serial interface.

...

> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5139,6 +5139,7 @@ M: Dongchun Zhu <dongchun.zhu@mediatek.com>
> L: linux-media@vger.kernel.org
> T: git git://linuxtv.org/media_tree.git
> S: Maintained
> +F: drivers/media/i2c/dw9768.c
> F: Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.yaml

Had you run parse-maintainers.pl?

I believe the order is wrong here.

...

> +#define DW9768_MAX_FOCUS_POS 1023

Is this value being dictated by amount of bits available in the hardware?
If so, I would rather put it in a form (1024 - 1) or alike to show that it has
10 bit resolution.

...

> +static int dw9768_set_dac(struct dw9768 *dw9768, u16 val)
> +{
> + struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> +
> + /* Write VCM position to registers */
> + return i2c_smbus_write_word_data(client, DW9768_MSB_ADDR,
> + swab16(val));

i2c_smbus_write_word_swapped() ?

> +}

...

> +static int dw9768_release(struct dw9768 *dw9768)
> +{
> + struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> + int ret, val;
> +

> + for (val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
> + val >= 0; val -= DW9768_MOVE_STEPS) {

Perhaps

val = round_down(dw9768->focus->val, DW9768_MOVE_STEPS);
for ( ; val >= 0; val -= DW9768_MOVE_STEPS) {

> + ret = dw9768_set_dac(dw9768, val);
> + if (ret) {

> + dev_err(&client->dev, "%s I2C failure: %d",
> + __func__, ret);

Do you need __func__? What for?

> + return ret;
> + }

> + usleep_range(DW9768_MOVE_DELAY_US,
> + DW9768_MOVE_DELAY_US + 1000);

It's exactly one line. Perhaps you have to check your editor settings.
And check entire code for a such.

> + }
> +
> + /*
> + * Wait for the motor to stabilize after the last movement
> + * to prevent the motor from shaking.
> + */
> + usleep_range(DW9768_STABLE_TIME_US - DW9768_MOVE_DELAY_US,
> + DW9768_STABLE_TIME_US - DW9768_MOVE_DELAY_US + 1000);
> +
> + ret = i2c_smbus_write_byte_data(client, DW9768_RING_PD_CONTROL_REG,
> + DW9768_PD_MODE_EN);
> + if (ret < 0)
> + return ret;
> +
> + /*
> + * DW9769 requires waiting delay time of t_OPR
> + * after PD reset takes place.
> + */
> + usleep_range(DW9768_T_OPR_US, DW9768_T_OPR_US + 100);
> +
> + return 0;
> +}

--
With Best Regards,
Andy Shevchenko