Re: [PATCH RESEND v7 2/2] Add support for OV5647 sensor.

[Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>]

Hi Sakari

On 2/7/2017 5:31 PM, Sakari Ailus wrote:
> Hi Ramiro,
> 
> On Mon, Feb 06, 2017 at 11:38:28AM +0000, Ramiro Oliveira wrote:
> ...
>>>> +	ret = ov5647_write_array(sd, ov5647_640x480,
>>>> +					ARRAY_SIZE(ov5647_640x480));
>>>> +	if (ret < 0) {
>>>> +		dev_err(&client->dev, "write sensor_default_regs error\n");
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	ov5647_set_virtual_channel(sd, 0);
>>>> +
>>>> +	ov5647_read(sd, 0x0100, &resetval);
>>>> +	if (!(resetval & 0x01)) {
>>>
>>> Can this ever happen? Streaming start is at the end of the register list.
>>>
>>
>> I'm not sure it can happen. It was just a safeguard, but I can remove it if you
>> think it's not necessary
> 
> You're not reading back the other registers either, albeit I'd check that
> the I2C accesses actually succeed. Generally the return values are ignored.
> 

So you're recommending I perform a random I2C access after power on to check the
system, and discard the read value? Or just drop this piece of code entirely?


>>
>>>> +		dev_err(&client->dev, "Device was in SW standby");
>>>> +		ov5647_write(sd, 0x0100, 0x01);
>>>> +	}
>>>> +
>>>> +	ov5647_write(sd, 0x4800, 0x04);
>>>> +	ov5647_stream_on(sd);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +/**
>>>> + * @short Control sensor power state
>>>> + * @param[in] sd v4l2 subdev
>>>> + * @param[in] on Sensor power
>>>> + * @return Error code
>>>> + */
>>>> +static int sensor_power(struct v4l2_subdev *sd, int on)
>>>> +{
>>>> +	int ret;
>>>> +	struct ov5647 *ov5647 = to_state(sd);
>>>> +	struct i2c_client *client = v4l2_get_subdevdata(sd);
>>>> +
>>>> +	ret = 0;
>>>> +	mutex_lock(&ov5647->lock);
>>>> +
>>>> +	if (on && !ov5647->power_count)	{
>>>> +		dev_dbg(&client->dev, "OV5647 power on\n");
>>>> +
>>>> +		clk_set_rate(ov5647->xclk, ov5647->xclk_freq);
>>>> +
>>>> +		ret = clk_prepare_enable(ov5647->xclk);
>>>> +		if (ret < 0) {
>>>> +			dev_err(ov5647->dev, "clk prepare enable failed\n");
>>>> +			goto out;
>>>> +		}
>>>> +
>>>> +		ret = ov5647_write_array(sd, sensor_oe_enable_regs,
>>>> +				ARRAY_SIZE(sensor_oe_enable_regs));
>>>> +		if (ret < 0) {
>>>> +			clk_disable_unprepare(ov5647->xclk);
>>>> +			dev_err(&client->dev,
>>>> +				"write sensor_oe_enable_regs error\n");
>>>> +			goto out;
>>>> +		}
>>>> +
>>>> +		ret = __sensor_init(sd);
>>>> +		if (ret < 0) {
>>>> +			clk_disable_unprepare(ov5647->xclk);
>>>> +			dev_err(&client->dev,
>>>> +				"Camera not available, check Power\n");
>>>> +			goto out;
>>>> +		}
>>>> +	} else if (!on && ov5647->power_count == 1) {
>>>> +		dev_dbg(&client->dev, "OV5647 power off\n");
>>>> +
>>>> +		dev_dbg(&client->dev, "disable oe\n");
>>>> +		ret = ov5647_write_array(sd, sensor_oe_disable_regs,
>>>> +				ARRAY_SIZE(sensor_oe_disable_regs));
>>>> +
>>>> +		if (ret < 0)
>>>> +			dev_dbg(&client->dev, "disable oe failed\n");
>>>> +
>>>> +		ret = set_sw_standby(sd, true);
>>>> +
>>>> +		if (ret < 0)
>>>> +			dev_dbg(&client->dev, "soft stby failed\n");
>>>> +
>>>> +		clk_disable_unprepare(ov5647->xclk);
>>>> +	}
>>>> +
>>>> +	/* Update the power count. */
>>>> +	ov5647->power_count += on ? 1 : -1;
>>>> +	WARN_ON(ov5647->power_count < 0);
>>>> +
>>>> +out:
>>>> +	mutex_unlock(&ov5647->lock);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_VIDEO_ADV_DEBUG
>>>> +/**
>>>> + * @short Get register value
>>>> + * @param[in] sd v4l2 subdev
>>>> + * @param[in] reg register struct
>>>> + * @return Error code
>>>> + */
>>>> +static int sensor_get_register(struct v4l2_subdev *sd,
>>>> +				struct v4l2_dbg_register *reg)
>>>> +{
>>>> +	unsigned char val = 0;
>>>> +	int ret;
>>>> +
>>>> +	ret = ov5647_read(sd, reg->reg & 0xff, &val);
>>>> +	if (ret != 0)
>>>> +		return ret;
>>>> +
>>>> +	reg->val = val;
>>>> +	reg->size = 1;
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +/**
>>>> + * @short Set register value
>>>> + * @param[in] sd v4l2 subdev
>>>> + * @param[in] reg register struct
>>>> + * @return Error code
>>>> + */
>>>> +static int sensor_set_register(struct v4l2_subdev *sd,
>>>> +				const struct v4l2_dbg_register *reg)
>>>> +{
>>>> +	return ov5647_write(sd, reg->reg & 0xff, reg->val & 0xff);
>>>> +}
>>>> +#endif
>>>> +
>>>> +/**
>>>> + * @short Subdev core operations registration
>>>> + */
>>>> +static const struct v4l2_subdev_core_ops sensor_core_ops = {
>>>> +	.s_power		= sensor_power,
>>>> +#ifdef CONFIG_VIDEO_ADV_DEBUG
>>>> +	.g_register		= sensor_get_register,
>>>> +	.s_register		= sensor_set_register,
>>>> +#endif
>>>> +};
>>>> +
>>>> +static int enum_mbus_code(struct v4l2_subdev *sd,
>>>> +				struct v4l2_subdev_pad_config *cfg,
>>>> +				struct v4l2_subdev_mbus_code_enum *code)
>>>> +{
>>>> +	if (code->index > 0)
>>>> +		return -EINVAL;
>>>> +
>>>> +	code->code = MEDIA_BUS_FMT_SBGGR8_1X8;
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static const struct v4l2_subdev_pad_ops subdev_pad_ops = {
>>>> +	.enum_mbus_code = enum_mbus_code,
>>>> +};
>>>> +
>>>> +
>>>> +/**
>>>> + * @short Subdev operations registration
>>>> + *
>>>> + */
>>>> +static const struct v4l2_subdev_ops subdev_ops = {
>>>> +	.core		= &sensor_core_ops,
>>>> +	.pad		= &subdev_pad_ops,
>>>
>>> You should implement s_stream() in video ops to control the streaming state.
>>>
>>> I don't know about this particular sensor, but on SMIA compliant sensors
>>> the SW standby means streaming is disabled. There seem to be additional
>>> registers as well; my educated guess is that writing all those to control
>>> streaming would be the right thing to do.
>>>
>>> The CSI-2 bus initialisation could fail if you start streaming right away
>>> when the sensor is powered on.
>>>
>>
>> I haven't had any error yet, but I'll add set_stream() and start streaming video
>> there, just to be sure.
> 
> It depends on the receiver. Some might work whereas some definitely don't.
> 
> Please see Documentation/media/kapi/csi2.rst .
> 

Thanks for the documentation, I'll implement s_stream as indicated.

-- 
Best Regards

Ramiro Oliveira
Ramiro.Oliveira@synopsys.com