HI Andy, thanks for addressing my comments on v6. Some more questions below. On Tue, Apr 10, 2018 at 11:48:44PM +0800, Andy Yeh wrote: > From: Alan Chiang > > DW9807 is a 10 bit DAC from Dongwoon, designed for linear > control of voice coil motor. > > This driver creates a V4L2 subdevice and > provides control to set the desired focus. > > Signed-off-by: Andy Yeh > --- > since v1: > - changed author. > since v2: > - addressed outstanding comments. > - enabled sequential write to update 2 registers in a single transaction. > since v3: > - addressed comments for v3. > - Remove redundant codes and declare some variables as constant variable. > - separate DT binding to another patch > since v4: > - sent patchset included DT binding with cover page > since v6: > - change the return code of i2c_check > - fix long cols exceed 80 chars > - remove #define DW9807_NAME since only used once > > MAINTAINERS | 7 + > drivers/media/i2c/Kconfig | 10 ++ > drivers/media/i2c/Makefile | 1 + > drivers/media/i2c/dw9807.c | 335 +++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 353 insertions(+) > create mode 100644 drivers/media/i2c/dw9807.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 845fc25..a339bb5 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -4385,6 +4385,13 @@ T: git git://linuxtv.org/media_tree.git > S: Maintained > F: drivers/media/i2c/dw9714.c > > +DONGWOON DW9807 LENS VOICE COIL DRIVER > +M: Sakari Ailus > +L: linux-media@vger.kernel.org > +T: git git://linuxtv.org/media_tree.git > +S: Maintained > +F: drivers/media/i2c/dw9807.c > + > DOUBLETALK DRIVER > M: "James R. Van Zandt" > L: blinux-list@redhat.com > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig > index cb5d7ff..fd01842 100644 > --- a/drivers/media/i2c/Kconfig > +++ b/drivers/media/i2c/Kconfig > @@ -325,6 +325,16 @@ config VIDEO_DW9714 > capability. This is designed for linear control of > voice coil motors, controlled via I2C serial interface. > > +config VIDEO_DW9807 > + tristate "DW9807 lens voice coil support" > + depends on I2C && VIDEO_V4L2 && MEDIA_CONTROLLER > + depends on VIDEO_V4L2_SUBDEV_API > + ---help--- iirc checkpatch warned me multiple times to prefer 'help' on '---help---' for newly introduced symbols. Could you check please (maybe with using the --strict option?) > + This is a driver for the DW9807 camera lens voice coil. > + DW9807 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_SAA7110 > tristate "Philips SAA7110 video decoder" > depends on VIDEO_V4L2 && I2C > diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile > index 548a9ef..1b62639 100644 > --- a/drivers/media/i2c/Makefile > +++ b/drivers/media/i2c/Makefile > @@ -23,6 +23,7 @@ obj-$(CONFIG_VIDEO_SAA7185) += saa7185.o > obj-$(CONFIG_VIDEO_SAA6752HS) += saa6752hs.o > obj-$(CONFIG_VIDEO_AD5820) += ad5820.o > obj-$(CONFIG_VIDEO_DW9714) += dw9714.o > +obj-$(CONFIG_VIDEO_DW9807) += dw9807.o > obj-$(CONFIG_VIDEO_ADV7170) += adv7170.o > obj-$(CONFIG_VIDEO_ADV7175) += adv7175.o > obj-$(CONFIG_VIDEO_ADV7180) += adv7180.o > diff --git a/drivers/media/i2c/dw9807.c b/drivers/media/i2c/dw9807.c > new file mode 100644 > index 0000000..062c30f > --- /dev/null > +++ b/drivers/media/i2c/dw9807.c > @@ -0,0 +1,335 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (C) 2018 Intel Corporation > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define DW9807_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 DW9807_FOCUS_STEPS 1 > +/* > + * This acts as the minimum granularity of lens movement. > + * Keep this value power of 2, so the control steps can be > + * uniformly adjusted for gradual lens movement, with desired > + * number of control steps. > + */ > +#define DW9807_CTRL_STEPS 16 > +#define DW9807_CTRL_DELAY_US 1000 > + > +#define DW9807_CTL_ADDR 0x02 > +/* > + * DW9807 separates two registers to control the VCM position. > + * One for MSB value, another is LSB value. > + */ > +#define DW9807_MSB_ADDR 0x03 > +#define DW9807_LSB_ADDR 0x04 > +#define DW9807_STATUS_ADDR 0x05 > +#define DW9807_MODE_ADDR 0x06 > +#define DW9807_RESONANCE_ADDR 0x07 > + > +#define MAX_RETRY 10 > + > +struct dw9807_device { > + struct v4l2_ctrl_handler ctrls_vcm; > + struct v4l2_subdev sd; > + u16 current_val; > +}; > + > +static inline struct dw9807_device *sd_to_dw9807_vcm( > + struct v4l2_subdev *subdev) > +{ > + return container_of(subdev, struct dw9807_device, sd); > +} > + > +static int dw9807_i2c_check(struct i2c_client *client) > +{ > + const char status_addr = DW9807_STATUS_ADDR; > + char status_result; > + int ret; > + > + ret = i2c_master_send(client, (const char *)&status_addr, > + sizeof(status_addr)); As reported by checkpatch, please fix alignement to the first open brace, and as per Tomasz comment remove the cast > + if (ret < 0) { > + dev_err(&client->dev, "I2C write STATUS address fail ret = %d\n", > + ret); > + return ret; > + } > + > + ret = i2c_master_recv(client, (char *)&status_result, > + sizeof(status_result)); Align the last argument to the first open brace. ret = i2c_master_recv(client, (char *)&status_result, sizeof(status_result)); > + if (ret != sizeof(status_result)) { My comment on i2c functions return values applies to i2c_master_recv() as well. Please just check for (ret < 0) here > + dev_err(&client->dev, "I2C read STATUS value fail ret=%d\n", The previous errror message has spaces in between 'ret','=' and '%d'. Please be consistent. > + ret); > + return ret; > + } > + > + return status_result; > +} > + > +static int dw9807_set_dac(struct i2c_client *client, u16 data) > +{ > + const char tx_data[3] = { > + DW9807_MSB_ADDR, ((data >> 8) & 0x03), (data & 0xff) > + }; > + int ret, retry = 0; > + > + /* > + * According to the datasheet, need to check the bus status before we > + * write VCM position. This ensure that we really write the value > + * into the register > + */ > + while ((ret = dw9807_i2c_check(client)) != 0) { > + if (ret < 0) > + return ret; > + > + if (MAX_RETRY == ++retry) { > + dev_err(&client->dev, > + "Cannot do the write operation because VCM is busy\n"); Nit: this is over 80 cols, it's fine, but I think you can really shorten the error messag without losing context. > + return -EIO; > + } > + usleep_range(DW9807_CTRL_DELAY_US, DW9807_CTRL_DELAY_US + 10); mmm, I wonder if a sleep range of 10usecs is really a strict requirement. Have a look at Documentation/timers/timers-howto.txt. With such a small range you're likely fire some unrequired interrupt. If I got this right, here you're just polling a register every 1msec-ish (usleep_range(1000, 1010)). I think you can enlarge the range safely (maybe lowering the number of retries if you wish to) and give more space to coalesce your wakeup with others. What is a good range? Good question. How effective is this to have your wakeup coalesced with others? I think this greatly depends on the system you're running on and its load at this specific time. So I would reply to both questions with "not sure", but I let you consider if you could enlarge your range to say 1000-1500 usec at least. > + } > + > + /* Write VCM position to registers */ > + ret = i2c_master_send(client, tx_data, sizeof(tx_data)); > + if (ret != sizeof(tx_data)) { As per previous comments, check for ret < 0 > + if (ret < 0) { > + dev_err(&client->dev, > + "I2C write MSB fail ret=%d\n", ret); > + return ret; > + } else { There cannot be any else case here as i2c_master_send returns < 0 or sizeof(tx_data) only. > + dev_err(&client->dev, "I2C write MSB fail, transmission size is not equal the size expected\n"); > + return -EIO; > + } > + } > + > + return 0; > +} > + > +static int dw9807_set_ctrl(struct v4l2_ctrl *ctrl) > +{ > + struct dw9807_device *dev_vcm = container_of(ctrl->handler, > + struct dw9807_device, ctrls_vcm); > + > + if (ctrl->id == V4L2_CID_FOCUS_ABSOLUTE) { > + struct i2c_client *client = v4l2_get_subdevdata(&dev_vcm->sd); > + > + dev_vcm->current_val = ctrl->val; > + return dw9807_set_dac(client, ctrl->val); > + } > + > + return -EINVAL; > +} > + > +static const struct v4l2_ctrl_ops dw9807_vcm_ctrl_ops = { > + .s_ctrl = dw9807_set_ctrl, > +}; > + > +static int dw9807_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh) > +{ > + int rval; > + > + rval = pm_runtime_get_sync(sd->dev); > + if (rval < 0) { > + pm_runtime_put_noidle(sd->dev); > + return rval; > + } > + > + return 0; > +} > + > +static int dw9807_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh) > +{ > + pm_runtime_put(sd->dev); > + > + return 0; > +} > + > +static const struct v4l2_subdev_internal_ops dw9807_int_ops = { > + .open = dw9807_open, > + .close = dw9807_close, > +}; > + > +static const struct v4l2_subdev_ops dw9807_ops = { }; > + > +static void dw9807_subdev_cleanup(struct dw9807_device *dw9807_dev) > +{ > + v4l2_async_unregister_subdev(&dw9807_dev->sd); > + v4l2_ctrl_handler_free(&dw9807_dev->ctrls_vcm); > + media_entity_cleanup(&dw9807_dev->sd.entity); > +} > + > +static int dw9807_init_controls(struct dw9807_device *dev_vcm) > +{ > + struct v4l2_ctrl_handler *hdl = &dev_vcm->ctrls_vcm; > + const struct v4l2_ctrl_ops *ops = &dw9807_vcm_ctrl_ops; > + struct i2c_client *client = v4l2_get_subdevdata(&dev_vcm->sd); > + > + v4l2_ctrl_handler_init(hdl, 1); > + > + v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE, > + 0, DW9807_MAX_FOCUS_POS, DW9807_FOCUS_STEPS, 0); > + > + dev_vcm->sd.ctrl_handler = hdl; > + if (hdl->error) { > + dev_err(&client->dev, "%s fail error: 0x%x\n", > + __func__, hdl->error); > + return hdl->error; > + } > + > + return 0; > +} > + > +static int dw9807_probe(struct i2c_client *client) > +{ > + struct dw9807_device *dw9807_dev; > + int rval; > + > + dw9807_dev = devm_kzalloc(&client->dev, sizeof(*dw9807_dev), > + GFP_KERNEL); > + if (!dw9807_dev) > + return -ENOMEM; > + > + v4l2_i2c_subdev_init(&dw9807_dev->sd, client, &dw9807_ops); > + dw9807_dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE; > + dw9807_dev->sd.internal_ops = &dw9807_int_ops; > + > + rval = dw9807_init_controls(dw9807_dev); > + if (rval) > + goto err_cleanup; > + > + rval = media_entity_pads_init(&dw9807_dev->sd.entity, 0, NULL); > + if (rval < 0) > + goto err_cleanup; > + > + dw9807_dev->sd.entity.function = MEDIA_ENT_F_LENS; Not super sure here, Sakari may confirm or not, but you don't have pads, you don't have pad operations, why are initializing entity pads and depend on MEDIA_CONTROLLER in Kconfig? I -think- you can remove these lines above here. > + > + rval = v4l2_async_register_subdev(&dw9807_dev->sd); > + if (rval < 0) > + goto err_cleanup; > + > + pm_runtime_set_active(&client->dev); > + pm_runtime_enable(&client->dev); > + pm_runtime_idle(&client->dev); > + > + return 0; > + > +err_cleanup: > + dw9807_subdev_cleanup(dw9807_dev); > + > + return rval; > +} > + > +static int dw9807_remove(struct i2c_client *client) > +{ > + struct v4l2_subdev *sd = i2c_get_clientdata(client); > + struct dw9807_device *dw9807_dev = sd_to_dw9807_vcm(sd); > + > + pm_runtime_disable(&client->dev); > + pm_runtime_set_suspended(&client->dev); > + > + dw9807_subdev_cleanup(dw9807_dev); > + > + return 0; > +} > + > +/* > + * This function sets the vcm position, so it consumes least current > + * The lens position is gradually moved in units of DW9807_CTRL_STEPS, > + * to make the movements smoothly. > + */ > +static int __maybe_unused dw9807_vcm_suspend(struct device *dev) > +{ > + struct i2c_client *client = to_i2c_client(dev); > + struct v4l2_subdev *sd = i2c_get_clientdata(client); > + struct dw9807_device *dw9807_dev = sd_to_dw9807_vcm(sd); > + const char tx_data[2] = { DW9807_CTL_ADDR, 0x01 }; > + int ret, val; > + > + for (val = dw9807_dev->current_val & ~(DW9807_CTRL_STEPS - 1); > + val >= 0; val -= DW9807_CTRL_STEPS) { > + ret = dw9807_set_dac(client, val); > + if (ret) > + dev_err_once(dev, "%s I2C failure: %d", __func__, ret); > + usleep_range(DW9807_CTRL_DELAY_US, DW9807_CTRL_DELAY_US + 10); ditto > + } > + > + /* Power down */ > + ret = i2c_master_send(client, tx_data, sizeof(tx_data)); > + ditch this empty line please > + if (ret != sizeof(tx_data)) { ditto, check for ret < 0 > + dev_err(&client->dev, "I2C write CTL fail\n"); > + return -EIO; consider returning ret to propagate i2c error > + } > + > + return 0; > +} > + > +/* > + * 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 DW9807_CTRL_STEPS, > + * to make the movements smoothly. > + */ > +static int __maybe_unused dw9807_vcm_resume(struct device *dev) > +{ > + struct i2c_client *client = to_i2c_client(dev); > + struct v4l2_subdev *sd = i2c_get_clientdata(client); > + struct dw9807_device *dw9807_dev = sd_to_dw9807_vcm(sd); > + const char tx_data[2] = { DW9807_CTL_ADDR, 0x00 }; > + int ret, val; > + > + /* Power on */ > + ret = i2c_master_send(client, tx_data, sizeof(tx_data)); > + if (ret != sizeof(tx_data)) { ditto, check for ret < 0 > + dev_err(&client->dev, "I2C write CTL fail\n"); > + return -EIO; consider returning ret to propagate i2c error > + } > + > + for (val = dw9807_dev->current_val % DW9807_CTRL_STEPS; > + val < dw9807_dev->current_val + DW9807_CTRL_STEPS - 1; > + val += DW9807_CTRL_STEPS) { > + ret = dw9807_set_dac(client, val); > + if (ret) > + dev_err_ratelimited(dev, "%s I2C failure: %d", > + __func__, ret); > + usleep_range(DW9807_CTRL_DELAY_US, DW9807_CTRL_DELAY_US + 10); ditto > + } > + > + return 0; > +} > + > +static const struct of_device_id dw9807_of_table[] = { > + { .compatible = "dongwoon,dw9807" }, > + { { 0 } } > +}; > +MODULE_DEVICE_TABLE(of, dw9807_of_table); > + > +static const struct dev_pm_ops dw9807_pm_ops = { > + SET_SYSTEM_SLEEP_PM_OPS(dw9807_vcm_suspend, dw9807_vcm_resume) > + SET_RUNTIME_PM_OPS(dw9807_vcm_suspend, dw9807_vcm_resume, NULL) > +}; > + > +static struct i2c_driver dw9807_i2c_driver = { > + .driver = { > + .name = "dw9807", > + .pm = &dw9807_pm_ops, > + .of_match_table = dw9807_of_table, > + }, > + .probe_new = dw9807_probe, > + .remove = dw9807_remove, > +}; > + > +module_i2c_driver(dw9807_i2c_driver); > + > +MODULE_AUTHOR("Chiang, Alan "); > +MODULE_DESCRIPTION("DW9807 VCM driver"); > +MODULE_LICENSE("GPL v2"); > -- > 2.7.4 >