Hi Dongchun, Sakari,
On Mon, May 18, 2020 at 09:27:31PM +0800, Dongchun Zhu wrote:
> Add a V4L2 sub-device driver for DW9768 voice coil motor, providing
> control to set the desired focus via IIC serial interface.
>
> Signed-off-by: Dongchun Zhu <dongchun.zhu@xxxxxxxxxxxx>
> ---
> MAINTAINERS | 1 +
> drivers/media/i2c/Kconfig | 13 ++
> drivers/media/i2c/Makefile | 1 +
> drivers/media/i2c/dw9768.c | 515 +++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 530 insertions(+)
> create mode 100644 drivers/media/i2c/dw9768.c
[snip]
> +/*
> + * DW9768_AAC_PRESC_REG & DW9768_AAC_TIME_REG determine VCM operation time.
> + * If DW9768_AAC_PRESC_REG is 0x41, and DW9768_AAC_TIME_REG is 0x39, VCM mode
> + * would be AAC3, Operation Time would be 0.70xTvib, that is 8.40ms.
> + */
> +#define DW9768_MOVE_DELAY_US 8400
> +#define DW9768_STABLE_TIME_US 20000
These times are only valid with the specific settings mentioned in the
comment. If one sets different settings in DT, the driver would apply
incorrect delays. Rather than hardcoded, they should be computed based
on the configured values.
That said, I wonder if we're not digging too deep now. Sakari, do you
think we could take a step back, remove the optional DT properties and
just support the fixed values for now, so that we can get a basic driver
upstream first without doubling the effort?
> +
> +static const char * const dw9768_supply_names[] = {
> + "vin", /* I2C I/O interface power */
> + "vdd", /* VCM power */
> +};
> +
> +/* dw9768 device structure */
> +struct dw9768 {
> + struct regulator_bulk_data supplies[ARRAY_SIZE(dw9768_supply_names)];
> + struct v4l2_ctrl_handler ctrls;
> + struct v4l2_ctrl *focus;
> + struct v4l2_subdev sd;
> +
> + u32 aac_mode;
> + u32 aac_timing;
> + u32 clock_dividing_rate;
> + bool aac_mode_control_enable;
> + bool aact_cnt_select_enable;
> + bool clock_dividing_rate_select_enable;
nit: Separate types from names with just 1 space.
> +};
> +
> +static inline struct dw9768 *sd_to_dw9768(struct v4l2_subdev *subdev)
> +{
> + return container_of(subdev, struct dw9768, sd);
> +}
> +
> +struct regval_list {
> + u8 reg_num;
> + u8 value;
> +};
> +
> +static int dw9768_read_smbus(struct dw9768 *dw9768, unsigned char reg,
> + unsigned char *val)
> +{
> + struct i2c_client *client = v4l2_get_subdevdata(&dw9768->sd);
> + int ret;
> +
> + ret = i2c_smbus_read_byte_data(client, reg);
> +
> + if (ret < 0)
> + return ret;
> +
> + *val = (unsigned char)ret;
> +
> + return 0;
> +}
Why do we need this function? Couldn't we just call
i2c_smbus_read_byte_data() directly?
[snip]
> +static int dw9768_probe(struct i2c_client *client)
> +{
> + struct device *dev = &client->dev;
> + struct dw9768 *dw9768;
> + unsigned int aac_mode_select;
> + unsigned int aac_timing_select;
> + unsigned int clock_dividing_rate_select;
> + unsigned int i;
> + int ret;
> +
> + dw9768 = devm_kzalloc(dev, sizeof(*dw9768), GFP_KERNEL);
> + if (!dw9768)
> + return -ENOMEM;
> +
> + v4l2_i2c_subdev_init(&dw9768->sd, client, &dw9768_ops);
> + dw9768->aac_mode_control_enable = false;
> + dw9768->aact_cnt_select_enable = false;
> + dw9768->clock_dividing_rate_select_enable = false;
devm_kzalloc() initializes the memory to zero, so no need to set anything
to false explicitly.
> +
> + /* Optional indication of AAC mode select */
> + ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-mode",
> + &aac_mode_select);
> +
> + if (!ret) {
> + dw9768->aac_mode_control_enable = true;
> + dw9768->aac_mode = aac_mode_select;
How about making aac_mode a signed int and assigning -1 by
default? Then we don't need two separate fields in the struct.
> + }
> +
> + /* Optional indication of VCM internal clock dividing rate select */
> + ret = fwnode_property_read_u32(dev_fwnode(dev),
> + "dongwoon,clock-dividing-rate",
> + &clock_dividing_rate_select);
> +
> + if (!ret) {
> + dw9768->clock_dividing_rate_select_enable = true;
> + dw9768->clock_dividing_rate = clock_dividing_rate_select;
Ditto.
> + }
> +
> + /* Optional indication of AAC Timing */
> + ret = fwnode_property_read_u32(dev_fwnode(dev), "dongwoon,aac-timing",
> + &aac_timing_select);
> +
> + if (!ret) {
> + dw9768->aact_cnt_select_enable = true;
> + dw9768->aac_timing = aac_timing_select;
Ditto.
> + }
> +
> + for (i = 0; i < ARRAY_SIZE(dw9768_supply_names); i++)
> + dw9768->supplies[i].supply = dw9768_supply_names[i];
> +
> + ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(dw9768_supply_names),
> + dw9768->supplies);
> + if (ret) {
> + dev_err(dev, "failed to get regulators\n");
> + return ret;
> + }
> +
> + ret = dw9768_init_controls(dw9768);
> + if (ret)
> + goto entity_cleanup;
> +
> + dw9768->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> + dw9768->sd.internal_ops = &dw9768_int_ops;
> +
> + ret = media_entity_pads_init(&dw9768->sd.entity, 0, NULL);
> + if (ret < 0)
> + goto entity_cleanup;
> +
> + dw9768->sd.entity.function = MEDIA_ENT_F_LENS;
> +
> + pm_runtime_enable(dev);
> + if (!pm_runtime_enabled(dev)) {
> + ret = dw9768_runtime_resume(dev);
> + if (ret < 0) {
> + dev_err(dev, "failed to power on: %d\n", ret);
> + goto entity_cleanup;
> + }
> + }
> +
> + ret = v4l2_async_register_subdev(&dw9768->sd);
> + if (ret < 0)
> + goto entity_cleanup;
> +
> + return 0;
> +
> +entity_cleanup:
Need to power off if the code above powered on.
> + v4l2_ctrl_handler_free(&dw9768->ctrls);
> + media_entity_cleanup(&dw9768->sd.entity);
> + return ret;
> +}
> +
> +static int dw9768_remove(struct i2c_client *client)
> +{
> + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> + struct dw9768 *dw9768 = sd_to_dw9768(sd);
> +
> + pm_runtime_disable(&client->dev);
First the device must be unregistered from the userspace. Otherwise there
is a race condition that risks the userspace accessing the device while the
deinitialization is happening.
Best regards,
Tomasz
