Hi Tomasz,
On Fri, 2019-08-23 at 17:17 +0900, Tomasz Figa wrote:
> Hi Dongchun,
>
> On Mon, Jul 08, 2019 at 06:06:41PM +0800, dongchun.zhu@xxxxxxxxxxxx wrote:
> > From: Dongchun Zhu <dongchun.zhu@xxxxxxxxxxxx>
> >
> > This patch adds a V4L2 sub-device driver for DW9768 lens voice coil,
> > and provides control to set the desired focus.
> >
> > The DW9807 is a 10 bit DAC from Dongwoon, designed for linear
> > control of voice coil motor.
> >
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@xxxxxxxxxxxx>
> > ---
> > MAINTAINERS | 1 +
> > drivers/media/i2c/Kconfig | 10 +
> > drivers/media/i2c/Makefile | 1 +
> > drivers/media/i2c/dw9768.c | 458 +++++++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 470 insertions(+)
> > create mode 100644 drivers/media/i2c/dw9768.c
> >
>
> Thanks for the patch! Please see my comments inline.
>
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 8f6ac93..17152d7 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -4877,6 +4877,7 @@ M: Dongchun Zhu <dongchun.zhu@xxxxxxxxxxxx>
> > L: linux-media@xxxxxxxxxxxxxxx
> > T: git git://linuxtv.org/media_tree.git
> > S: Maintained
> > +F: drivers/media/i2c/dw9768.c
> > F: Documentation/devicetree/bindings/media/i2c/dongwoon,dw9768.txt
> >
> > DONGWOON DW9807 LENS VOICE COIL DRIVER
> > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> > index 7793358..8ff6c95 100644
> > --- a/drivers/media/i2c/Kconfig
> > +++ b/drivers/media/i2c/Kconfig
> > @@ -1014,6 +1014,16 @@ config VIDEO_DW9714
> > capability. This is designed for linear control of
> > voice coil motors, controlled via I2C serial interface.
> >
> > +config VIDEO_DW9768
> > + tristate "DW9768 lens voice coil support"
> > + depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> > + depends on VIDEO_V4L2_SUBDEV_API
> > + help
> > + This is a driver for the DW9768 camera lens voice coil.
> > + DW9768 is a 10 bit DAC with 100mA output current sink
> > + capability. This is designed for linear control of
> > + voice coil motors, controlled via I2C serial interface.
> > +
> > config VIDEO_DW9807_VCM
> > tristate "DW9807 lens voice coil support"
> > depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER
> > diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> > index d8ad9da..944fbf6 100644
> > --- a/drivers/media/i2c/Makefile
> > +++ b/drivers/media/i2c/Makefile
> > @@ -24,6 +24,7 @@ obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o
> > obj-$(CONFIG_VIDEO_AD5820) += ad5820.o
> > obj-$(CONFIG_VIDEO_AK7375) += ak7375.o
> > obj-$(CONFIG_VIDEO_DW9714) += dw9714.o
> > +obj-$(CONFIG_VIDEO_DW9768) += dw9768.o
> > obj-$(CONFIG_VIDEO_DW9807_VCM) += dw9807-vcm.o
> > obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o
> > obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o
> > diff --git a/drivers/media/i2c/dw9768.c b/drivers/media/i2c/dw9768.c
> > new file mode 100644
> > index 0000000..f5b5591
> > --- /dev/null
> > +++ b/drivers/media/i2c/dw9768.c
> > @@ -0,0 +1,458 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2018 MediaTek Inc.
> > + */
> > +
> > +#include <linux/delay.h>
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/pm_runtime.h>
> > +#include <media/v4l2-ctrls.h>
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-subdev.h>
> > +
> > +#define DW9768_VOLTAGE_ANALOG 2800000
>
> This is a platform detail and should be defined in the platform data, for
> example DTS on platforms using DT.
>
Thanks for your reminder.
This would be fixed in next release.
> > +#define DW9768_NAME "dw9768"
>
> The chip we seem to be using this driver for is called gt9769. Shouldn't we
> call the driver the same?
>
It is also called DW9768 from camera module specification, which was
initially confirmed with vendor.
> > +#define DW9768_MAX_FOCUS_POS 1023
> > +/*
> > + * This sets the minimum granularity for the focus positions.
> > + * A value of 1 gives maximum accuracy for a desired focus position
> > + */
> > +#define DW9768_FOCUS_STEPS 1
> > +
> > +#define DW9768_CTRL_DELAY_US 5000
> > +
> > +#define DW9768_REG_DAC_MSB 0x03
> > +#define DW9768_REG_DAC_LSB 0x04
> > +#define DW9768_REG_NULL 0xff
> > +
> > +#define DW9768_DAC_SHIFT 8
> > +
> > +#define DW9768_REG_VALUE_16BIT 2
>
> This driver seems to always write 16-bit values. Can we simplify it to just
> always assume so?
>
Fixed in next release.
> > +
> > +/* dw9768 device structure */
> > +struct dw9768_device {
> > + struct v4l2_ctrl_handler ctrls;
> > + struct v4l2_subdev sd;
> > + struct regulator *analog_regulator;
> > + /*
> > + * Serialize control access, get/set format, get selection
> > + * and start streaming.
> > + */
> > + struct mutex power_lock;
> > +
> > + int power_count;
> > + bool standby;
> > +};
> > +
> > +static inline struct dw9768_device *to_dw9768_vcm(struct v4l2_ctrl *ctrl)
> > +{
> > + return container_of(ctrl->handler, struct dw9768_device, ctrls);
> > +}
> > +
> > +static inline struct dw9768_device *sd_to_dw9768_vcm(struct v4l2_subdev *subdev)
> > +{
> > + return container_of(subdev, struct dw9768_device, sd);
> > +}
> > +
> > +static int dw9768_i2c_write(struct dw9768_device *dw9768_dev, u8 *data,
> > + int size)
> > +{
> > + struct i2c_client *client = v4l2_get_subdevdata(&dw9768_dev->sd);
> > + struct i2c_msg msg;
> > + u8 *w_buf = NULL;
> > + u8 retry_cnt = 3;
> > + int ret;
> > +
> > + if (!client->adapter)
> > + return -ENODEV;
>
> This isn't possible.
>
Removed in next release.
> > +
> > + if (size != 1 && size != 2)
> > + return -EINVAL;
>
> All the calls always pass 2.
>
Fixed in next release.
> > +
> > + memset(&msg, 0, sizeof(struct i2c_msg));
> > +
> > + w_buf = kzalloc(size, GFP_KERNEL);
> > + if (!w_buf)
> > + return -1;
>
> The size is fixed to 2. Is it necessary to allocate the buffer dynamically?
>
Fixed in next release.
> > +
> > + memcpy(w_buf, data, size);
> > +
> > + msg.addr = client->addr;
> > + msg.flags = 0;
> > + msg.len = size;
> > + msg.buf = w_buf;
>
> Actually, why don't we just use data directly?
>
Fixed in next release.
> > +
> > + do {
> > + ret = i2c_transfer(client->adapter, &msg, 1);
> > + if (ret != 1)
> > + dev_err(&client->dev, "write fail, ret:%d, retry:%d\n",
> > + ret, retry_cnt);
> > + else
> > + break;
> > + retry_cnt--;
> > + } while (retry_cnt != 0);
> > +
> > + if (retry_cnt == 0) {
> > + dev_err(&client->dev, "i2c write fail(%d)\n", ret);
> > + return -EIO;
> > + }
>
> Why do we need to handle retries here? I don't see the hardware datasheet
> refer to any need to do those. Are you seeing some issues with transfers?
>
This is used to processing i2c transfer showing abnormality in some
cases.
Retries handler would be removed in next release.
> > +
> > + kfree(w_buf);
> > +
> > + return 0;
> > +}
> > +
> > +static int dw9768_release(struct dw9768_device *dw9768_dev)
> > +{
> > + unsigned char i;
> > + int ret;
> > +
> > + char puSendCmdArray[4][2] = {
>
> Please use the correct kernel coding style.
>
Fixed in next release.
> > + {0x02, 0x00}, {DW9768_REG_NULL, DW9768_REG_NULL},
> > + {0x01, 0x00}, {DW9768_REG_NULL, DW9768_REG_NULL},
>
> We only check the first element for this specific value, so we don't need
> to initialize the second one.
>
> Also, could we call it DW9768_CMD_DELAY instead?
>
> Also, please define macros for the magic values used in the array.
>
This would be fixed in next release.
> > + };
> > +
> > + for (i = 0; i < (sizeof(puSendCmdArray) / sizeof(char)) /
> > + (sizeof(puSendCmdArray[0]) / sizeof(char)); i++) {
>
> Wouldn't ARRAY_SIZE() work here?
>
Fixed in next release.
> > + if (puSendCmdArray[i][0] != DW9768_REG_NULL) {
> > + ret = dw9768_i2c_write(dw9768_dev, puSendCmdArray[i],
> > + DW9768_REG_VALUE_16BIT);
> > + if (ret < 0)
> > + return ret;
>
> Hmm, isn't this command array actually a pair of addreses and values?
> Please define a struct for the entries.
>
> Could we just use i2c_smbus_write_byte_data() instead of the custom
> dw9768_i2c_write()?
>
Thanks for great suggestion.
We would try i2c_smbus_write_byte_data API for write i2c register.
> > + } else {
> > + usleep_range(DW9768_CTRL_DELAY_US,
> > + DW9768_CTRL_DELAY_US + 100);
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int dw9768_init(struct dw9768_device *dw9768_dev)
> > +{
> > + unsigned char i;
> > + int ret;
> > +
> > + char puSendCmdArray[5][2] = {
> > + {0x02, 0x02}, {DW9768_REG_NULL, DW9768_REG_NULL},
> > + {0x06, 0x41}, {0x07, 0x39}, {DW9768_REG_NULL, DW9768_REG_NULL},
> > + };
> > +
> > + for (i = 0; i < (sizeof(puSendCmdArray) / sizeof(char)) /
> > + (sizeof(puSendCmdArray[0]) / sizeof(char)); i++) {
> > + if (puSendCmdArray[i][0] != DW9768_REG_NULL) {
> > + ret = dw9768_i2c_write(dw9768_dev, puSendCmdArray[i],
> > + DW9768_REG_VALUE_16BIT);
> > + if (ret < 0)
> > + return ret;
> > + } else {
> > + usleep_range(DW9768_CTRL_DELAY_US,
> > + DW9768_CTRL_DELAY_US + 100);
> > + }
> > + }
>
> The code here is duplicated, just different command array is used. Could we
> move the command array handling to a helper function? (+ all the comments
> I mentioned above)
>
Fixed in next release.
> > +
> > + return 0;
> > +}
> > +
> > +/*
> > + * Power handling
> > + */
> > +static int dw9768_power_off(struct dw9768_device *dw9768_dev, bool standby)
> > +{
> > + struct i2c_client *client = v4l2_get_subdevdata(&dw9768_dev->sd);
> > + int ret;
> > +
> > + /*
> > + * Go to standby first as real power off my be denied by the hardware
> > + * (single power line control for both dw9768_dev and sensor).
>
> What do you mean here? The regulator subsystem already properly handles
> reference counting.
>
Understood.
> > + */
> > + if (standby) {
> > + dw9768_dev->standby = true;
> > + ret = dw9768_release(dw9768_dev);
> > + if (ret)
> > + dev_err(&client->dev, "dw9768_release failed!\n");
>
> Shouldn't we always call this when we power off?
>
> > + }
> > + ret = regulator_disable(dw9768_dev->analog_regulator);
> > + if (ret)
> > + return ret;
> > +
> > + return 0;
> > +}
> > +
> > +static int dw9768_power_on(struct dw9768_device *dw9768_dev, bool restore)
> > +{
> > + int ret;
> > +
> > + ret = regulator_enable(dw9768_dev->analog_regulator);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if (restore) {
> > + /* Restore the hardware settings. */
> > + dw9768_dev->standby = false;
> > + ret = dw9768_init(dw9768_dev);
> > + if (ret < 0)
> > + goto fail;
>
> Shouldn't we always call this when we power on, without any condition?
>
> > + }
> > +
> > + return 0;
> > +
> > +fail:
> > + dw9768_dev->standby = true;
> > + regulator_disable(dw9768_dev->analog_regulator);
> > +
> > + return ret;
> > +}
>
> The two functions above should be called from the runtime PM suspend/resume
> callbacks.
>
Fixed in next release.
> > +
> > +/*
> > + * Calculate status word and write it to the device based on current
> > + * values of V4L2 controls. It is assumed that the stored V4L2 control
> > + * values are properly limited and rounded.
> > + */
> > +static int dw9768_update_hw(struct dw9768_device *dw9768_dev, u16 val)
> > +{
> > + unsigned char i;
> > + int ret;
> > +
> > + char puSendCmdArray[2][2] = {
> > + {DW9768_REG_DAC_MSB, (char)(val >> DW9768_DAC_SHIFT)},
> > + {DW9768_REG_DAC_LSB, (char)(val & 0xFF)},
> > + };
> > +
> > + for (i = 0; i < (sizeof(puSendCmdArray) / sizeof(char)) /
> > + (sizeof(puSendCmdArray[0]) / sizeof(char)); i++) {
> > + ret = dw9768_i2c_write(dw9768_dev, puSendCmdArray[i],
> > + DW9768_REG_VALUE_16BIT);
> > + if (ret)
> > + return ret;
> > + }
>
> Since the two registers are actually one after another, perhaps you could
> use i2c_smbus_write_block_data() to batch them into one transfer?
>
We would have a try.
> > +
> > + return 0;
> > +}
> > +
> > +static int dw9768_set_ctrl(struct v4l2_ctrl *ctrl)
> > +{
> > + struct dw9768_device *dw9768_dev = to_dw9768_vcm(ctrl);
> > +
> > + if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE)
> > + return dw9768_update_hw(dw9768_dev, ctrl->val);
>
> I think we could just inline the contents of that function here, because
> this function doesn't do anything else.
>
Fixed in next release.
> > +
> > + return 0;
> > +}
> > +
> > +static const struct v4l2_ctrl_ops dw9768_vcm_ctrl_ops = {
> > + .s_ctrl = dw9768_set_ctrl,
> > +};
> > +
> > +static int
> > +dw9768_set_power(struct v4l2_subdev *subdev, int on)
> > +{
> > + struct dw9768_device *dw9768_dev = sd_to_dw9768_vcm(subdev);
> > + int ret = 0;
> > +
> > + mutex_lock(&dw9768_dev->power_lock);
> > +
> > + /*
> > + * If the power count is modified from 0 to != 0 or from != 0 to 0,
> > + * update the power state.
> > + */
> > + if (dw9768_dev->power_count == !on) {
> > + ret = on ? dw9768_power_on(dw9768_dev, true) :
> > + dw9768_power_off(dw9768_dev, true);
> > + if (ret < 0)
> > + goto done;
> > + }
>
> If we use runtime PM, we get the reference count handling done for us by
> the subsystem.
>
Understood.
> > +
> > + /* Update the power count. */
> > + dw9768_dev->power_count += on ? 1 : -1;
> > + WARN_ON(dw9768_dev->power_count < 0);
> > +
> > +done:
> > + mutex_unlock(&dw9768_dev->power_lock);
> > + return ret;
> > +}
> > +
> > +static int dw9768_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> > +{
> > + return dw9768_set_power(sd, 1);
>
> We could just call pm_runtime_get_sync() here.
>
Fixed in next release.
> > +}
> > +
> > +static int dw9768_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> > +{
> > + return dw9768_set_power(sd, 0);
>
> And pm_runtime_put() here.
>
Fixed in next release.
> > +}
> > +
> > +static const struct v4l2_subdev_internal_ops dw9768_int_ops = {
> > + .open = dw9768_open,
> > + .close = dw9768_close,
> > +};
> > +
> > +static const struct v4l2_subdev_ops dw9768_ops = { };
> > +
> > +static void dw9768_subdev_cleanup(struct dw9768_device *dw9768_dev)
> > +{
> > + v4l2_async_unregister_subdev(&dw9768_dev->sd);
> > + v4l2_ctrl_handler_free(&dw9768_dev->ctrls);
> > + media_entity_cleanup(&dw9768_dev->sd.entity);
> > +}
> > +
> > +static int dw9768_init_controls(struct dw9768_device *dw9768_dev)
> > +{
> > + struct v4l2_ctrl_handler *hdl = &dw9768_dev->ctrls;
> > + const struct v4l2_ctrl_ops *ops = &dw9768_vcm_ctrl_ops;
> > +
> > + v4l2_ctrl_handler_init(hdl, 1);
> > +
> > + v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE,
> > + 0, DW9768_MAX_FOCUS_POS, DW9768_FOCUS_STEPS, 0);
> > +
> > + if (hdl->error) {
> > + dev_err(dw9768_dev->sd.dev, "%s fail error: 0x%x\n",
> > + __func__, hdl->error);
> > + return hdl->error;
> > + }
> > +
> > + dw9768_dev->sd.ctrl_handler = hdl;
> > +
> > + return 0;
> > +}
> > +
> > +static int dw9768_probe(struct i2c_client *client)
> > +{
> > + struct device *dev = &client->dev;
> > + struct dw9768_device *dw9768_dev;
>
> nit: Could we drop the _device and _dev suffixes to shorten the names?
>
Fixed in next release.
> > + int rval;
> > +
> > + dw9768_dev = devm_kzalloc(&client->dev, sizeof(*dw9768_dev),
> > + GFP_KERNEL);
> > + if (!dw9768_dev)
> > + return -ENOMEM;
> > +
> > + dw9768_dev->analog_regulator = devm_regulator_get(dev, "afvdd");
>
> "avfdd" is the name on our camera module, not the chip. It should be "vdd".
>
Fixed in next release.
> > + if (IS_ERR(dw9768_dev->analog_regulator)) {
> > + dev_err(dev, "cannot get analog regulator\n");
> > + return PTR_ERR(dw9768_dev->analog_regulator);
> > + }
>
> We also need 1 more regulator here for the I2C interface. The datasheet
> calls it "vin".
>
Fixed in next release.
> > +
> > + rval = regulator_set_voltage(dw9768_dev->analog_regulator,
> > + DW9768_VOLTAGE_ANALOG,
> > + DW9768_VOLTAGE_ANALOG);
> > + if (rval < 0) {
> > + dev_err(dev, "cannot set analog voltage\n");
> > + return rval;
> > + }
>
> This should be set in the platform code. For example, on systems using DT
> it can be done by setting the regulator min and max constraints in the DTS.
>
Fixed in next release.
> > +
> > + mutex_init(&dw9768_dev->power_lock);
> > +
> > + v4l2_i2c_subdev_init(&dw9768_dev->sd, client, &dw9768_ops);
> > + dw9768_dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > + dw9768_dev->sd.internal_ops = &dw9768_int_ops;
> > +
> > + rval = dw9768_init_controls(dw9768_dev);
> > + if (rval)
> > + goto err_cleanup;
> > +
> > + rval = media_entity_pads_init(&dw9768_dev->sd.entity, 0, NULL);
> > + if (rval < 0)
> > + goto err_cleanup;
> > +
> > + dw9768_dev->sd.entity.function = MEDIA_ENT_F_LENS;
> > +
> > + rval = v4l2_async_register_subdev(&dw9768_dev->sd);
> > + if (rval < 0)
> > + goto err_cleanup;
> > +
> > + pm_runtime_set_active(dev);
>
> We shouldn't call this if we didn't fully power up the device ourselves and
> I don't see the code above enabling the regulator. Given the privacy LED
> concerns, we actually shouldn't attempt to power on in probe.
>
Understood.
> > + pm_runtime_enable(dev);
> > + pm_runtime_idle(dev);
>
> Ditto for idle, which is not needed if the device was not set active.
>
Fixed in next release.
> > +
> > + return 0;
> > +
> > +err_cleanup:
> > + mutex_destroy(&dw9768_dev->power_lock);
> > + dw9768_subdev_cleanup(dw9768_dev);
> > + dev_err(dev, "Probe failed: %d\n", rval);
> > + return rval;
> > +}
> > +
> > +static int dw9768_remove(struct i2c_client *client)
> > +{
> > + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > + struct dw9768_device *dw9768_dev = sd_to_dw9768_vcm(sd);
> > +
> > + pm_runtime_disable(&client->dev);
>
> Technically we need to check if (!pm_runtime_state_suspended()) and power
> down manually and set_suspended if that was the case.
>
Fixed in next release.
> > + dw9768_subdev_cleanup(dw9768_dev);
> > +
> > + return 0;
> > +}
> > +
> > +/*
> > + * This function sets the vcm position, so it consumes least current
> > + * The lens position is gradually moved in units of DW9768_CTRL_STEPS,
> > + * to make the movements smoothly.
> > + */
> > +static int __maybe_unused dw9768_vcm_suspend(struct device *dev)
> > +{
> > + struct i2c_client *client = to_i2c_client(dev);
> > + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > + struct dw9768_device *dw9768_dev = sd_to_dw9768_vcm(sd);
> > +
> > + if (!dw9768_dev->power_count)
> > + return 0;
> > +
> > + return dw9768_power_off(dw9768_dev, false);
> > +}
> > +
> > +/*
> > + * This function sets the vcm position to the value set by the user
> > + * through v4l2_ctrl_ops s_ctrl handler
> > + * The lens position is gradually moved in units of DW9768_CTRL_STEPS,
> > + * to make the movements smoothly.
> > + */
> > +static int __maybe_unused dw9768_vcm_resume(struct device *dev)
> > +{
> > + struct i2c_client *client = to_i2c_client(dev);
> > + struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > + struct dw9768_device *dw9768_dev = sd_to_dw9768_vcm(sd);
> > +
> > + if (!dw9768_dev->power_count)
> > + return 0;
> > +
> > + return dw9768_power_on(dw9768_dev, true);
> > +}
> > +
> > +static const struct i2c_device_id dw9768_id_table[] = {
> > + { DW9768_NAME, 0 },
> > + { { 0 } }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, dw9768_id_table);
> > +
> > +static const struct of_device_id dw9768_of_table[] = {
> > + { .compatible = "dongwoon,dw9768" },
> > + { { 0 } }
> > +};
> > +MODULE_DEVICE_TABLE(of, dw9768_of_table);
> > +
> > +static const struct dev_pm_ops dw9768_pm_ops = {
> > + SET_SYSTEM_SLEEP_PM_OPS(dw9768_vcm_suspend, dw9768_vcm_resume)
> > + SET_RUNTIME_PM_OPS(dw9768_vcm_suspend, dw9768_vcm_resume, NULL)
>
> Okay, so we already provided the callbacks, but we never called
> pm_runtime_get/put().
>
> Also, I'm not sure if we can provide the same callbacks for runtime and
> system PM ops, but I think we could use pm_runtime_force_suspend() and
> pm_runtime_force_resume() as system ones to achieve the same.
>
SET_SYSTEM_SLEEP_PM_OPS would use pm_runtime_force_suspend/resume in
next release.
> Best regards,
> Tomasz
