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Message-ID: <e4ce5644-4f44-4c46-219a-cac2126dc8ba@synopsys.com>
Date: Wed, 8 Feb 2017 09:56:12 +0000
From: Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
To: Sakari Ailus <sakari.ailus@....fi>,
Ramiro Oliveira <Ramiro.Oliveira@...opsys.com>
CC: Sakari Ailus <sakari.ailus@...ux.intel.com>,
<linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<devicetree@...r.kernel.org>, <CARLOS.PALMINHA@...opsys.com>,
"David S. Miller" <davem@...emloft.net>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Guenter Roeck <linux@...ck-us.net>,
Hans Verkuil <hans.verkuil@...co.com>,
Mark Rutland <mark.rutland@....com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
"Pavel Machek" <pavel@....cz>,
Robert Jarzmik <robert.jarzmik@...e.fr>,
Rob Herring <robh+dt@...nel.org>,
Steve Longerbeam <slongerbeam@...il.com>
Subject: Re: [PATCH RESEND v7 2/2] Add support for OV5647 sensor.
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@...opsys.com
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