On Tue, Mar 6, 2018 at 5:40 PM, Sakari Ailus
<sakari.ailus@xxxxxxxxxxxxxxx> wrote:
> Hi Tomasz and Andy,
>
> On Sat, Mar 03, 2018 at 12:43:59AM +0900, Tomasz Figa wrote:
> ...
>> > +static int imx258_set_ctrl(struct v4l2_ctrl *ctrl)
>> > +{
>> > + struct imx258 *imx258 =
>> > + container_of(ctrl->handler, struct imx258, ctrl_handler);
>> > + struct i2c_client *client = v4l2_get_subdevdata(&imx258->sd);
>> > + int ret = 0;
>> > + /*
>> > + * Applying V4L2 control value only happens
>> > + * when power is up for streaming
>> > + */
>> > + if (pm_runtime_get_if_in_use(&client->dev) <= 0)
>> > + return 0;
>>
>> I thought we decided to fix this to handle disabled runtime PM properly.
>
> Good point. I bet this is a problem in a few other drivers, too. How would
> you fix that? Check for zero only?
>
bool need_runtime_put;
ret = pm_runtime_get_if_in_use(&client->dev);
if (ret <= 0 && ret != -EINVAL)
return ret;
need_runtime_put = ret > 0;
// Do stuff ...
if (need_runtime_put)
pm_runtime_put(&client->dev);
I don't like how ugly it is, but it appears to be the only way to
handle this correctly.
> ...
>
>> [snip]
>> > +/* Initialize control handlers */
>> > +static int imx258_init_controls(struct imx258 *imx258)
>> > +{
>> > + struct i2c_client *client = v4l2_get_subdevdata(&imx258->sd);
>> > + struct v4l2_ctrl_handler *ctrl_hdlr;
>> > + s64 exposure_max;
>> > + s64 vblank_def;
>> > + s64 vblank_min;
>> > + s64 pixel_rate_min;
>> > + s64 pixel_rate_max;
>> > + int ret;
>> > +
>> > + ctrl_hdlr = &imx258->ctrl_handler;
>> > + ret = v4l2_ctrl_handler_init(ctrl_hdlr, 8);
>> > + if (ret)
>>
>> Missing error message.
>>
>> > + return ret;
>> > +
>> > + mutex_init(&imx258->mutex);
>> > + ctrl_hdlr->lock = &imx258->mutex;
>> > + imx258->link_freq = v4l2_ctrl_new_int_menu(ctrl_hdlr,
>> > + &imx258_ctrl_ops,
>> > + V4L2_CID_LINK_FREQ,
>> > + ARRAY_SIZE(link_freq_menu_items) - 1,
>> > + 0,
>> > + link_freq_menu_items);
>> > +
>> > + if (!imx258->link_freq) {
>> > + ret = -EINVAL;
>>
>> Missing error message.
>
> I wouldn't add an error message here. Typically you'd need that information
> at development time only, never after that. v4l2_ctrl_new_int_menu(), as
> other control framework functions creating new controls, can fail due to
> memory allocation failure (which is already vocally reported) or due to bad
> parameters (that are constants).
>
> I'd rather do:
>
> if (!imx258->link_freq)
> ... |= ...;
>
> It simplifies error handling and removes the need for goto.
Hmm, I'm not sure I understand your suggestion. Do you perhaps mean
if (imx258->link_freq) {
// Do stuff that dereferences imx258->link_freq
}
// ...
if (ctrl_hdlr->error) {
// Check for error only here, at the end of control initialization.
}
then it would be better indeed.
>
>>
>> > + goto error;
>> > + }
>> > +
>> > + imx258->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>> > +
>> > + pixel_rate_max = link_freq_to_pixel_rate(link_freq_menu_items[0]);
>> > + pixel_rate_min = link_freq_to_pixel_rate(link_freq_menu_items[1]);
>> > + /* By default, PIXEL_RATE is read only */
>> > + imx258->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &imx258_ctrl_ops,
>> > + V4L2_CID_PIXEL_RATE,
>> > + pixel_rate_min, pixel_rate_max,
>> > + 1, pixel_rate_max);
>> > +
>> > +
>> > + vblank_def = imx258->cur_mode->vts_def - imx258->cur_mode->height;
>> > + vblank_min = imx258->cur_mode->vts_min - imx258->cur_mode->height;
>> > + imx258->vblank = v4l2_ctrl_new_std(
>> > + ctrl_hdlr, &imx258_ctrl_ops, V4L2_CID_VBLANK,
>> > + vblank_min,
>> > + IMX258_VTS_MAX - imx258->cur_mode->height, 1,
>> > + vblank_def);
>> > +
>> > + imx258->hblank = v4l2_ctrl_new_std(
>> > + ctrl_hdlr, &imx258_ctrl_ops, V4L2_CID_HBLANK,
>> > + IMX258_PPL_650MHZ - imx258->cur_mode->width,
>> > + IMX258_PPL_650MHZ - imx258->cur_mode->width,
>> > + 1,
>> > + IMX258_PPL_650MHZ - imx258->cur_mode->width);
>> > +
>> > + if (!imx258->hblank) {
>> > + ret = -EINVAL;
>> > + goto error;
>> > + }
>>
>> Why checking hblank, but not other controls? I think in this case just
>> the general check for ctrl_hdlr->error should be enough.
>
> There's no need to access most other controls (except blank and link_freq).
> The flags field is set for hblank below, therefore the check.
Ah, right, I missed the dereference.
>
>>
>> > +
>> > + imx258->hblank->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>> > +
>> > + exposure_max = imx258->cur_mode->vts_def - 8;
>> > + imx258->exposure = v4l2_ctrl_new_std(
>> > + ctrl_hdlr, &imx258_ctrl_ops,
>> > + V4L2_CID_EXPOSURE, IMX258_EXPOSURE_MIN,
>> > + IMX258_EXPOSURE_MAX, IMX258_EXPOSURE_STEP,
>> > + IMX258_EXPOSURE_DEFAULT);
>> > +
>> > + v4l2_ctrl_new_std(ctrl_hdlr, &imx258_ctrl_ops, V4L2_CID_ANALOGUE_GAIN,
>> > + IMX258_ANA_GAIN_MIN, IMX258_ANA_GAIN_MAX,
>> > + IMX258_ANA_GAIN_STEP, IMX258_ANA_GAIN_DEFAULT);
>> > +
>> > + v4l2_ctrl_new_std(ctrl_hdlr, &imx258_ctrl_ops, V4L2_CID_DIGITAL_GAIN,
>> > + IMX258_DGTL_GAIN_MIN, IMX258_DGTL_GAIN_MAX,
>> > + IMX258_DGTL_GAIN_STEP, IMX258_DGTL_GAIN_DEFAULT);
>> > +
>> > + v4l2_ctrl_new_std_menu_items(ctrl_hdlr, &imx258_ctrl_ops,
>> > + V4L2_CID_TEST_PATTERN,
>> > + ARRAY_SIZE(imx258_test_pattern_menu) - 1,
>> > + 0, 0, imx258_test_pattern_menu);
>> > +
>> > + if (ctrl_hdlr->error) {
>> > + ret = ctrl_hdlr->error;
>> > + dev_err(&client->dev, "%s control init failed (%d)\n",
>> > + __func__, ret);
>> > + goto error;
>> > + }
>> > +
>> > + imx258->sd.ctrl_handler = ctrl_hdlr;
>> > +
>> > + return 0;
>> > +
>> > +error:
>> > + v4l2_ctrl_handler_free(ctrl_hdlr);
>> > + mutex_destroy(&imx258->mutex);
>> > +
>> > + return ret;
>> > +}
>> > +
>> > +static void imx258_free_controls(struct imx258 *imx258)
>> > +{
>> > + v4l2_ctrl_handler_free(imx258->sd.ctrl_handler);
>> > + mutex_destroy(&imx258->mutex);
>> > +}
>> > +
>> > +static int imx258_probe(struct i2c_client *client)
>> > +{
>> > + struct imx258 *imx258;
>> > + int ret;
>> > + u32 val = 0;
>> > +
>> > + device_property_read_u32(&client->dev, "clock-frequency", &val);
>> > + if (val != 19200000)
>>
>> Would be nice to print some error.
>>
>> > + return -EINVAL;
>> > +
>> > + imx258 = devm_kzalloc(&client->dev, sizeof(*imx258), GFP_KERNEL);
>> > + if (!imx258)
>> > + return -ENOMEM;
>> > +
>> > + /* Initialize subdev */
>> > + v4l2_i2c_subdev_init(&imx258->sd, client, &imx258_subdev_ops);
>> > +
>> > + /* Check module identity */
>> > + ret = imx258_identify_module(imx258);
>> > + if (ret)
>> > + return ret;
>> > +
>> > + /* Set default mode to max resolution */
>> > + imx258->cur_mode = &supported_modes[0];
>> > +
>> > + ret = imx258_init_controls(imx258);
>> > + if (ret)
>> > + return ret;
>> > +
>> > + /* Initialize subdev */
>> > + imx258->sd.internal_ops = &imx258_internal_ops;
>> > + imx258->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>> > + imx258->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
>> > +
>> > + /* Initialize source pad */
>> > + imx258->pad.flags = MEDIA_PAD_FL_SOURCE;
>> > +
>> > + ret = media_entity_pads_init(&imx258->sd.entity, 1, &imx258->pad);
>> > + if (ret) {
>> > + dev_err(&client->dev, "%s failed:%d\n", __func__, ret);
>>
>> This isn't a very useful error message. "media_entity_pads_init()
>> failed: %d\n" would make more sense.
>
> Considering media_entity_pads_init() only fails due to bad parameters and
> those would not change during the operation of the driver, IMO any error
> message here is not useful.
I guess it's a personal preference. I don't mind removing it, though.
Best regards,
Tomasz
