Hi Tomasz,
On Wed, 2020-06-10 at 19:44 +0000, Tomasz Figa wrote:
> Hi Dongchun,
>
> On Sat, May 23, 2020 at 04:41:03PM +0800, Dongchun Zhu wrote:
> > Add a V4L2 sub-device driver for OV02A10 image sensor.
> >
> > Signed-off-by: Dongchun Zhu <dongchun.zhu@xxxxxxxxxxxx>
> > ---
> > MAINTAINERS | 1 +
> > drivers/media/i2c/Kconfig | 13 +
> > drivers/media/i2c/Makefile | 1 +
> > drivers/media/i2c/ov02a10.c | 1025 +++++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 1040 insertions(+)
> > create mode 100644 drivers/media/i2c/ov02a10.c
> >
>
> Thank you for the patch. Please see my comments inline.
>
> [snip]
> > diff --git a/drivers/media/i2c/ov02a10.c b/drivers/media/i2c/ov02a10.c
> > new file mode 100644
> > index 0000000..160a0b5
> > --- /dev/null
> > +++ b/drivers/media/i2c/ov02a10.c
> [snip]
> > +static const char * const ov02a10_test_pattern_menu[] = {
> > + "Disabled",
> > + "Color Bar",
>
> nit: We should normalize this to one of the standard names. What is the
> pattern on this sensor? Is it perhaps "Eight Vertical Colour Bars"?
>
Yes. It is one kind of 'Eight Vertical Colour Bars'.
This pattern is called as 'MIPI color bar' per the datasheet.
Can we here use 'Vertical Color Bar' or 'MIPI Color Bar'?
> > +};
> [snip]
> > +static int ov02a10_set_fmt(struct v4l2_subdev *sd,
> > + struct v4l2_subdev_pad_config *cfg,
> > + struct v4l2_subdev_format *fmt)
> > +{
> > + struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > + struct v4l2_mbus_framefmt *mbus_fmt = &fmt->format;
> > +
> > + mutex_lock(&ov02a10->mutex);
> > +
>
>
> Don't we need to handle the case when fmt->which is V4L2_SUBDEV_FORMAT_TRY,
> which is used for trying the format, but not applying it to the hardware?
>
Got it :-)
> > + if (ov02a10->streaming) {
> > + mutex_unlock(&ov02a10->mutex);
> > + return -EBUSY;
> > + }
> > +
> > + /* Only one sensor mode supported */
> > + mbus_fmt->code = ov02a10->fmt.code;
> > + ov02a10_fill_fmt(ov02a10->cur_mode, mbus_fmt);
> > + ov02a10->fmt = fmt->format;
> > +
> > + mutex_unlock(&ov02a10->mutex);
> > +
> > + return 0;
> > +}
> > +
> > +static int ov02a10_get_fmt(struct v4l2_subdev *sd,
> > + struct v4l2_subdev_pad_config *cfg,
> > + struct v4l2_subdev_format *fmt)
> > +{
> > + struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > + struct v4l2_mbus_framefmt *mbus_fmt = &fmt->format;
> > +
> > + mutex_lock(&ov02a10->mutex);
> > +
> > + fmt->format = ov02a10->fmt;
>
> Ditto.
>
> > + mbus_fmt->code = ov02a10->fmt.code;
> > + ov02a10_fill_fmt(ov02a10->cur_mode, mbus_fmt);
> > +
> > + mutex_unlock(&ov02a10->mutex);
> > +
> > + return 0;
> > +}
> > +
> > +static int ov02a10_enum_mbus_code(struct v4l2_subdev *sd,
> > + struct v4l2_subdev_pad_config *cfg,
> > + struct v4l2_subdev_mbus_code_enum *code)
> > +{
> > + struct ov02a10 *ov02a10 = to_ov02a10(sd);
> > +
> > + if (code->index >= ARRAY_SIZE(supported_modes))
> > + return -EINVAL;
>
> Hmm, supported_modes[] doesn't seem to hold the information about mbus
> codes. Should this just perhaps be "!= 0"?
>
Understood.
> > +
> > + code->code = ov02a10->fmt.code;
> > +
> > + return 0;
> > +}
> [snip]
> > +static int ov02a10_entity_init_cfg(struct v4l2_subdev *sd,
> > + struct v4l2_subdev_pad_config *cfg)
> > +{
> > + struct v4l2_subdev_format fmt = {
> > + .which = cfg ? V4L2_SUBDEV_FORMAT_TRY : V4L2_SUBDEV_FORMAT_ACTIVE,
> > + .format = {
> > + .width = 1600,
> > + .height = 1200,
> > + }
> > + };
> > +
> > + ov02a10_set_fmt(sd, cfg, &fmt);
> > +
> > + return 0;
> > +}
> > +
>
> I'm not familiar with this init_cfg operation and the documentation is very
> sparse about it. Sakari, is this a correct implementation?
>
> [snip]
> > +static int ov02a10_set_test_pattern(struct ov02a10 *ov02a10, int pattern)
> > +{
> > + struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > + int ret;
> > +
> > + ret = i2c_smbus_write_byte_data(client, REG_PAGE_SWITCH, REG_ENABLE);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = i2c_smbus_write_byte_data(client, OV02A10_REG_TEST_PATTERN,
> > + pattern);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = i2c_smbus_write_byte_data(client, REG_GLOBAL_EFFECTIVE,
> > + REG_ENABLE);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return i2c_smbus_write_byte_data(client, REG_SC_CTRL_MODE,
> > + SC_CTRL_MODE_STREAMING);
>
> Why is this needed? Does writing the test pattern register stop streaming?
>
Looking back to the setting history, I found it was suggested by OV.
I would leave your question to OV, and update their feedback.
> [snip]
> > +static int ov02a10_initialize_controls(struct ov02a10 *ov02a10)
> > +{
> > + struct i2c_client *client = v4l2_get_subdevdata(&ov02a10->subdev);
> > + const struct ov02a10_mode *mode;
> > + struct v4l2_ctrl_handler *handler;
> > + struct v4l2_ctrl *ctrl;
> > + u64 exposure_max;
> > + u32 pixel_rate;
> > + int ret;
> > +
> > + handler = &ov02a10->ctrl_handler;
> > + mode = ov02a10->cur_mode;
> > + ret = v4l2_ctrl_handler_init(handler, 7);
> > + if (ret)
> > + return ret;
> > +
> > + handler->lock = &ov02a10->mutex;
> > +
> > + ctrl = v4l2_ctrl_new_int_menu(handler, NULL, V4L2_CID_LINK_FREQ, 0, 0,
> > + link_freq_menu_items);
> > + if (ctrl)
> > + ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > +
> > + pixel_rate = to_pixel_rate(0);
> > + v4l2_ctrl_new_std(handler, NULL, V4L2_CID_PIXEL_RATE, 0, pixel_rate, 1,
> > + pixel_rate);
> > +
> > + exposure_max = mode->vts_def - 4;
> > + ov02a10->exposure = v4l2_ctrl_new_std(handler, &ov02a10_ctrl_ops,
> > + V4L2_CID_EXPOSURE,
> > + OV02A10_EXPOSURE_MIN,
> > + exposure_max,
> > + OV02A10_EXPOSURE_STEP,
> > + mode->exp_def);
> > +
> > + v4l2_ctrl_new_std(handler, &ov02a10_ctrl_ops,
> > + V4L2_CID_ANALOGUE_GAIN,
> > + OV02A10_GAIN_MIN,
> > + OV02A10_GAIN_MAX,
> > + OV02A10_GAIN_STEP,
> > + OV02A10_GAIN_DEFAULT);
> > +
> > + v4l2_ctrl_new_std_menu_items(handler, &ov02a10_ctrl_ops,
> > + V4L2_CID_TEST_PATTERN,
> > + ARRAY_SIZE(ov02a10_test_pattern_menu) - 1,
> > + 0, 0, ov02a10_test_pattern_menu);
> > +
>
> I can see that we're missing some controls here now, VBLANK and HBLANK if I
> remember correctly. Even though read-only, some userspace need those to
> get information about how the sensor operates.
>
Yes. I made a mistake.
> > + if (handler->error) {
> > + ret = handler->error;
> > + dev_err(&client->dev, "failed to init controls(%d)\n", ret);
> > + goto err_free_handler;
> > + }
> > +
> > + ov02a10->subdev.ctrl_handler = handler;
> > +
> > + return 0;
> > +
> > +err_free_handler:
> > + v4l2_ctrl_handler_free(handler);
> > +
> > + return ret;
> > +}
> [snip]
> > + pm_runtime_enable(dev);
> > + if (!pm_runtime_enabled(dev)) {
> > + ret = ov02a10_power_on(dev);
> > + if (ret < 0) {
> > + dev_err(dev, "failed to power on: %d\n", ret);
> > + goto err_free_handler;
> > + }
> > + }
> > +
> > + ret = v4l2_async_register_subdev(&ov02a10->subdev);
> > + if (ret) {
> > + dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> > + if (!pm_runtime_enabled(dev))
> > + ov02a10_power_off(dev);
>
> Please don't mix inline and error-path error handling, as it makes it
> difficult to tell if it's correct. Please move this below the appropriate
> err label instead.
>
Fixed in next release.
> > + goto err_clean_entity;
> > + }
> > +
> > + return 0;
> > +
> > +err_clean_entity:
>
> If one calls pm_runtime_enable() in the probe path, one needs to call
> pm_runtime_disable() on the error and remove paths.
>
Yes, fixed in next release.
> > + media_entity_cleanup(&ov02a10->subdev.entity);
> > +err_free_handler:
> > + v4l2_ctrl_handler_free(ov02a10->subdev.ctrl_handler);
> > +err_destroy_mutex:
> > + mutex_destroy(&ov02a10->mutex);
> > +
> > + return ret;
> > +}
> > +
>
> Best regards,
> Tomasz
