Hi Jacopo,
On 22-08-18, Jacopo Mondi wrote:
> Hi Marco
>
> On Thu, Aug 18, 2022 at 04:47:09PM +0200, Marco Felsch wrote:
> > Add support to report the PIXEL_RATE so a host or bridge device can ask
> > the sensor.
> >
> > Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
> > ---
> > drivers/media/i2c/mt9m111.c | 15 ++++++++++++++-
> > 1 file changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c
> > index afc86efa9e3e..cdaf283e1309 100644
> > --- a/drivers/media/i2c/mt9m111.c
> > +++ b/drivers/media/i2c/mt9m111.c
> > @@ -908,6 +908,8 @@ static int mt9m111_s_ctrl(struct v4l2_ctrl *ctrl)
> > return mt9m111_set_test_pattern(mt9m111, ctrl->val);
> > case V4L2_CID_COLORFX:
> > return mt9m111_set_colorfx(mt9m111, ctrl->val);
> > + case V4L2_CID_PIXEL_RATE:
> > + return 0;
>
> By default PIXEL_RATE is read-only.
> Do you get a call to s_ctrl for it ?
You're absolutly right, we don't need to do this.
> > }
> >
> > return -EINVAL;
> > @@ -1249,6 +1251,7 @@ static int mt9m111_probe(struct i2c_client *client)
> > {
> > struct mt9m111 *mt9m111;
> > struct i2c_adapter *adapter = client->adapter;
> > + unsigned long mclk_rate;
> > int ret;
> >
> > if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
> > @@ -1271,6 +1274,13 @@ static int mt9m111_probe(struct i2c_client *client)
> > if (IS_ERR(mt9m111->clk))
> > return PTR_ERR(mt9m111->clk);
> >
> > + ret = clk_prepare_enable(mt9m111->clk);
> > + if (ret < 0)
> > + return ret;
> > +
>
> Do you need to enable clock to read its rate ?
Yes, accroding the API [1].
[1] https://elixir.bootlin.com/linux/v6.0-rc1/source/include/linux/clk.h#L682
> > + mclk_rate = clk_get_rate(mt9m111->clk);
> > + clk_disable_unprepare(mt9m111->clk);
> > +
> > mt9m111->regulator = devm_regulator_get(&client->dev, "vdd");
> > if (IS_ERR(mt9m111->regulator)) {
> > dev_err(&client->dev, "regulator not found: %ld\n",
> > @@ -1285,7 +1295,7 @@ static int mt9m111_probe(struct i2c_client *client)
> > mt9m111->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
> > V4L2_SUBDEV_FL_HAS_EVENTS;
> >
> > - v4l2_ctrl_handler_init(&mt9m111->hdl, 7);
> > + v4l2_ctrl_handler_init(&mt9m111->hdl, 8);
> > v4l2_ctrl_new_std(&mt9m111->hdl, &mt9m111_ctrl_ops,
> > V4L2_CID_VFLIP, 0, 1, 1, 0);
> > v4l2_ctrl_new_std(&mt9m111->hdl, &mt9m111_ctrl_ops,
> > @@ -1309,6 +1319,9 @@ static int mt9m111_probe(struct i2c_client *client)
> > BIT(V4L2_COLORFX_NEGATIVE) |
> > BIT(V4L2_COLORFX_SOLARIZATION)),
> > V4L2_COLORFX_NONE);
> > + v4l2_ctrl_new_std(&mt9m111->hdl, &mt9m111_ctrl_ops, V4L2_CID_PIXEL_RATE,
> > + mclk_rate, mclk_rate, 1, mclk_rate);
> > +
>
> I don't have a datasheet but it seems a little weird that the mclk
> frequency is the same as the pixel clock rate ?
I see your confusion here. I can only speak for the MT9M131 device which
is covered by this driver as well. This device is composed of a
internal-sensor and a internal-isp. The internal-sensor is clocked by
mclk/2 but the final image device/sensor output-fifo is clocked by mclk.
There are options to devide the output clock as well, but these options
are not enabled yet. So yes, the pixel clock rate == mclk rate. To avoid
confusion I could rename the mclk_rate to extclk_rate but then clock
request is not 100% correct since we are requesting a "mclk", this
should be "extclk".
Regards,
Marco
> > mt9m111->subdev.ctrl_handler = &mt9m111->hdl;
> > if (mt9m111->hdl.error) {
> > ret = mt9m111->hdl.error;
> > --
> > 2.30.2
> >
>
