Re: [PATCH V10 2/2] media: i2c: ov02a10: Add OV02A10 image sensor driver

[Dongchun Zhu <dongchun.zhu@mediatek.com>]

Hi Tomasz,

On Mon, 2020-06-29 at 12:27 +0200, Tomasz Figa wrote:
> On Mon, Jun 29, 2020 at 9:54 AM Dongchun Zhu <dongchun.zhu@mediatek.com> wrote:
> >
> > Hi Tomasz,
> >
> > On Thu, 2020-06-18 at 19:10 +0000, Tomasz Figa wrote:
> > > Hi Dongchun,
> > >
> > > On Mon, Jun 15, 2020 at 08:29:37PM +0800, Dongchun Zhu wrote:
> > > > Add a V4L2 sub-device driver for OV02A10 image sensor.
> > > >
> > > > Signed-off-by: Dongchun Zhu <dongchun.zhu@mediatek.com>
> > > > ---
> > > >  MAINTAINERS                 |    1 +
> > > >  drivers/media/i2c/Kconfig   |   13 +
> > > >  drivers/media/i2c/Makefile  |    1 +
> > > >  drivers/media/i2c/ov02a10.c | 1042 +++++++++++++++++++++++++++++++++++++++++++
> > > >  4 files changed, 1057 insertions(+)
> > > >  create mode 100644 drivers/media/i2c/ov02a10.c
> > > >
> > >
> > > Thank you for the patch. Please see my comments inline.
> > >
> >
> > [snip]
> >
> > > > +static int ov02a10_probe(struct i2c_client *client)
> > > > +{
> > > > +   struct device *dev = &client->dev;
> > > > +   struct ov02a10 *ov02a10;
> > > > +   unsigned int rotation;
> > > > +   unsigned int clock_lane_tx_speed;
> > > > +   unsigned int i;
> > > > +   int ret;
> > > > +
> > > > +   ov02a10 = devm_kzalloc(dev, sizeof(*ov02a10), GFP_KERNEL);
> > > > +   if (!ov02a10)
> > > > +           return -ENOMEM;
> > > > +
> > > > +   ret = ov02a10_check_hwcfg(dev, ov02a10);
> > > > +   if (ret) {
> > > > +           dev_err(dev, "failed to check HW configuration: %d", ret);
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   v4l2_i2c_subdev_init(&ov02a10->subdev, client, &ov02a10_subdev_ops);
> > > > +   ov02a10->mipi_clock_tx_speed = OV02A10_MIPI_TX_SPEED_DEFAULT;
> > > > +   ov02a10->fmt.code = MEDIA_BUS_FMT_SBGGR10_1X10;
> > > > +
> > > > +   /* Optional indication of physical rotation of sensor */
> > > > +   ret = fwnode_property_read_u32(dev_fwnode(dev), "rotation", &rotation);
> > > > +   if (!ret && rotation == 180) {
> > > > +           ov02a10->upside_down = true;
> > > > +           ov02a10->fmt.code = MEDIA_BUS_FMT_SRGGB10_1X10;
> > > > +   }
> > > > +
> > > > +   /* Optional indication of mipi TX speed */
> > > > +   ret = fwnode_property_read_u32(dev_fwnode(dev), "ovti,mipi-tx-speed",
> > > > +                                  &clock_lane_tx_speed);
> > > > +
> > > > +   if (!ret)
> > > > +           ov02a10->mipi_clock_tx_speed = clock_lane_tx_speed;
> > > > +
> > > > +   /* Get system clock (eclk) */
> > > > +   ov02a10->eclk = devm_clk_get(dev, "eclk");
> > > > +   if (IS_ERR(ov02a10->eclk)) {
> > > > +           ret = PTR_ERR(ov02a10->eclk);
> > > > +           dev_err(dev, "failed to get eclk %d\n", ret);
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
> > > > +                                  &ov02a10->eclk_freq);
> > > > +   if (ret) {
> > > > +           dev_err(dev, "failed to get eclk frequency\n");
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   ret = clk_set_rate(ov02a10->eclk, ov02a10->eclk_freq);
> > > > +   if (ret) {
> > > > +           dev_err(dev, "failed to set eclk frequency (24MHz)\n");
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   if (clk_get_rate(ov02a10->eclk) != OV02A10_ECLK_FREQ) {
> > > > +           dev_warn(dev, "wrong eclk frequency %d Hz, expected: %d Hz\n",
> > > > +                    ov02a10->eclk_freq, OV02A10_ECLK_FREQ);
> > > > +           return -EINVAL;
> > > > +   }
> > > > +
> > > > +   ov02a10->pd_gpio = devm_gpiod_get(dev, "powerdown", GPIOD_OUT_HIGH);
> > > > +   if (IS_ERR(ov02a10->pd_gpio)) {
> > > > +           ret = PTR_ERR(ov02a10->pd_gpio);
> > > > +           dev_err(dev, "failed to get powerdown-gpios %d\n", ret);
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   ov02a10->rst_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> > > > +   if (IS_ERR(ov02a10->rst_gpio)) {
> > > > +           ret = PTR_ERR(ov02a10->rst_gpio);
> > > > +           dev_err(dev, "failed to get reset-gpios %d\n", ret);
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   for (i = 0; i < ARRAY_SIZE(ov02a10_supply_names); i++)
> > > > +           ov02a10->supplies[i].supply = ov02a10_supply_names[i];
> > > > +
> > > > +   ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ov02a10_supply_names),
> > > > +                                 ov02a10->supplies);
> > > > +   if (ret) {
> > > > +           dev_err(dev, "failed to get regulators\n");
> > > > +           return ret;
> > > > +   }
> > > > +
> > > > +   mutex_init(&ov02a10->mutex);
> > > > +   ov02a10->cur_mode = &supported_modes[0];
> > > > +   ret = ov02a10_initialize_controls(ov02a10);
> > > > +   if (ret) {
> > > > +           dev_err(dev, "failed to initialize controls\n");
> > > > +           goto err_destroy_mutex;
> > > > +   }
> > > > +
> > > > +   ov02a10->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > > > +   ov02a10->subdev.entity.ops = &ov02a10_subdev_entity_ops;
> > > > +   ov02a10->subdev.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> > > > +   ov02a10->pad.flags = MEDIA_PAD_FL_SOURCE;
> > > > +   ret = media_entity_pads_init(&ov02a10->subdev.entity, 1, &ov02a10->pad);
> > > > +   if (ret < 0) {
> > > > +           dev_err(dev, "failed to init entity pads: %d", ret);
> > > > +           goto err_free_handler;
> > > > +   }
> > > > +
> > > > +   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_clean_entity;
> > > > +           }
> > > > +   }
> > > > +
> > > > +   ret = v4l2_async_register_subdev(&ov02a10->subdev);
> > > > +   if (ret) {
> > > > +           dev_err(dev, "failed to register V4L2 subdev: %d", ret);
> > > > +           goto err_power_off;
> > > > +   }
> > > > +
> > > > +   return 0;
> > > > +
> > > > +err_power_off:
> > > > +   pm_runtime_disable(dev);
> > > > +   if (!pm_runtime_enabled(dev))
> > >
> > > This would be always true, resulting in unbalanced power off. Moving
> > > pm_runtime_disable() after this if should work better.
> > >
> >
> > Pardon, do you mean that we shall use like this:
> > err_power_off:
> >         if (!pm_runtime_enabled(dev)) {
> >                 pm_runtime_disable(dev);
> >                 if (!pm_runtime_status_suspended(dev)
> >                         ov02a10_power_off(dev);
> >         }
> 
> Hmm, that wouldn't really work, because there is no reason to disable
> runtime PM if it's disabled already. I also noticed that we don't need
> to check pm_runtime_status_suspended() in the error path in probe,
> because we only ever attempt to power it on when runtime PM is
> disabled in kernel config. This would make the end result as:
> 
>          if (pm_runtime_enabled(dev))
>                  pm_runtime_disable(dev);
>          else
>                  ov02a10_power_off(dev);
> 

Thanks for the sharing.
It seems err_power_off section here helps balance the pm_runtime_enable
and pm_runtime_disable to keep dev->power.disable_depth right.
While runtime PM is disabled, ov02a10_power_off could also perform power
off instead of runtime PM.

> Best regards,
> Tomasz