Re: [V2, 2/2] media: i2c: Add DW9768 VCM driver

Hello Andy,

Thanks for the review. Please see the replies below.

On Mon, 2019-09-05 at 12:26 +0200, Andy Shevchenko wrote:

On Thu, Sep 05, 2019 at 03:21:42PM +0800, dongchun.zhu@mediatek.com wrote:

quoted

From: Dongchun Zhu <redacted>

This patch adds a V4L2 sub-device driver for DW9768 lens voice coil,
and provides control to set the desired focus.

The DW9768 is a 10 bit DAC with 100mA output current sink capability
from Dongwoon, designed for linear control of voice coil motor, and
controlled via I2C serial interface.

quoted

Signed-off-by: Dongchun Zhu <redacted>
---
 MAINTAINERS                |   1 +

This should go to the same patch, where you introduce a record in the MAINTAINERS database.

quoted

+#define DW9768_SET_POSITION_ADDR                0x03

Indentation issue.

Fixed in next release.

quoted

+static struct regval_list dw9768_init_regs[] = {
+{0x02, 0x02},
+{DW9768_CMD_DELAY, DW9768_CMD_DELAY},
+{0x06, 0x41},
+{0x07, 0x39},
+{DW9768_CMD_DELAY, DW9768_CMD_DELAY}, };
+
+static struct regval_list dw9768_release_regs[] = {
+{0x02, 0x00},
+{DW9768_CMD_DELAY, DW9768_CMD_DELAY},
+{0x01, 0x00},
+{DW9768_CMD_DELAY, DW9768_CMD_DELAY}, };
+
+static int dw9768_write_smbus(struct dw9768 *dw9768, unsigned char reg,
+      unsigned char value)
+{
+struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
+int ret;
+

quoted

+if (reg == DW9768_CMD_DELAY  && value == DW9768_CMD_DELAY)

Indentation issue.
But see other's comments.

quoted

+usleep_range(DW9768_CTRL_DELAY_US,
+     DW9768_CTRL_DELAY_US + 100);

quoted

+else

This needs an explanation.

Fixed in next release.

quoted

+ret = i2c_smbus_write_byte_data(client, reg, value);
+return ret;
+}

I'm wondering if we can benefit from regmap I²C API in this driver.

quoted

+static int __maybe_unused dw9768_vcm_suspend(struct device *dev) {

quoted

+struct i2c_client *client = to_i2c_client(dev);
+struct v4l2_subdev *sd = i2c_get_clientdata(client);

isn't is simple dev_get_drvdata() ?

As discussed in another group mail, even dev_set_drvdata() is set when
probe, the pointer that point to the private device struct changes when
using dev_get_drvdata() API.
Then resume/power on would result in kernel exception in
regulator_enable.

This is so weird.
We filed one Google issue to trace this behavior.
https://partnerissuetracker.corp.google.com/issues/147957975

I am wondering whether there is any condition of the use of
dev_get_drvdata().
I checked the other drivers and found that most devices that use
dev_get_drvdata() are platform devices or non i2c client devices.
So maybe dw9768 or other media/i2c devices cannot support
dev_get_drvdata()?

quoted

+struct dw9768 *dw9768 = sd_to_dw9768_vcm(sd);
+
+return dw9768_power_off(dw9768);
+}
+
+static int __maybe_unused dw9768_vcm_resume(struct device *dev) {

quoted

+struct i2c_client *client = to_i2c_client(dev);
+struct v4l2_subdev *sd = i2c_get_clientdata(client);

Ditto.

quoted

+struct dw9768 *dw9768 = sd_to_dw9768_vcm(sd);
+
+return dw9768_power_on(dw9768);
+}

quoted

+static const struct i2c_device_id dw9768_id_table[] = {
+{ DW9768_NAME, 0 },

quoted

+{ },

No comma.

This struct would be removed in next release.

quoted

+};

quoted

+static const struct of_device_id dw9768_of_table[] = {
+{ .compatible = "dongwoon,dw9768" },

quoted

+{ },

Ditto.

Fixed in next release.

quoted

+};

--
With Best Regards,
Andy Shevchenko


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