Hi Laurent,
Thanks for you reply.
I'd like to ask for advice about how to contrl "reset-pin", please
check the below comments.
On Tue, 2024-02-20 at 05:01 +0200, Laurent Pinchart wrote:
>
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
> Hi Zhi,
>
> On Tue, Feb 20, 2024 at 02:12:26AM +0000, Zhi Mao (毛智) wrote:
> > On Tue, 2024-02-06 at 20:45 +0200, Laurent Pinchart wrote:
> > > On Sun, Feb 04, 2024 at 02:15:38PM +0800, Zhi Mao wrote:
> > > > Add a V4L2 sub-device driver for Galaxycore GC08A3 image
> sensor.
> > > >
> > > > Signed-off-by: Zhi Mao <zhi.mao@xxxxxxxxxxxx>
> > > > ---
> > > > drivers/media/i2c/Kconfig | 10 +
> > > > drivers/media/i2c/Makefile | 1 +
> > > > drivers/media/i2c/gc08a3.c | 1448
> ++++++++++++++++++++++++++++++++++++
> > > > 3 files changed, 1459 insertions(+)
> > > > create mode 100644 drivers/media/i2c/gc08a3.c
>
> [snip]
>
> > > > diff --git a/drivers/media/i2c/gc08a3.c
> b/drivers/media/i2c/gc08a3.c
> > > > new file mode 100644
> > > > index 000000000000..3fc7fffb815c
> > > > --- /dev/null
> > > > +++ b/drivers/media/i2c/gc08a3.c
> > > > @@ -0,0 +1,1448 @@
>
> [snip]
>
> > > > +static int gc08a3_power_on(struct device *dev)
> > > > +{
> > > > +struct i2c_client *client = to_i2c_client(dev);
> > > > +struct v4l2_subdev *sd = i2c_get_clientdata(client);
> > > > +struct gc08a3 *gc08a3 = to_gc08a3(sd);
> > > > +int ret;
> > > > +
> > > > +ret = regulator_bulk_enable(ARRAY_SIZE(gc08a3_supply_name),
> > > > + gc08a3->supplies);
> > > > +if (ret < 0) {
> > > > +dev_err(gc08a3->dev, "failed to enable regulators: %d\n",
> ret);
> > > > +return ret;
> > > > +}
> > > > +
> > > > +ret = clk_prepare_enable(gc08a3->xclk);
> > > > +if (ret < 0) {
> > > > +regulator_bulk_disable(ARRAY_SIZE(gc08a3_supply_name),
> > > > + gc08a3->supplies);
> > > > +dev_err(gc08a3->dev, "clk prepare enable failed\n");
> > > > +return ret;
> > > > +}
> > > > +
> > > > +usleep_range(GC08A3_MIN_SLEEP_US, GC08A3_MAX_SLEEP_US);
> > > > +
> > > > +gpiod_set_value_cansleep(gc08a3->reset_gpio, 1);
> > >
> > > Are you asserting reset when powering on ? That sounds wrong, you
> should
> > > de-assert reset here (and acquire the reset gpio in probe() with
> > > GPIOD_OUT_HIGH). Drivers should use logical levels for GPIOs,
> setting a
> > > GPIO named "reset" to 1 should assert the reset signal, even if
> the
> > > physical signal is active low. You may have the wrong polarity in
> the
> > > device tree.
> >
> > According to the sensor power sequence sepc, "reset" pin should be
> pull
> > from low to high after "dovdd/dvdd/avdd" power on, so I follow this
> > power sequece to pull "reset" pin high in software flow.
>
> From a hardware point of view that's right, but the Linux kernel
> handles
> logical level of GPIOs. If a GPIO is named "reset", it is expected
> that
> calling
>
> gpiod_set_value_cansleep(gc08a3->reset_gpio, 1);
>
> will "assert" the reset signal, setting it to a logical "reset =
> true"
> level. This maps to the hardware 0V output level, as the signal is
> active-low. To achieve this, define the reset GPIO as active low in
> DT,
> and the GPIO framework will invert the signal for you. You should
> then
> call
>
> gpiod_set_value_cansleep(gc08a3->reset_gpio, 1);
>
> in the driver when you want to assert reset (set it to 0V), and
>
> gpiod_set_value_cansleep(gc08a3->reset_gpio, 0);
>
> when you want to deassert it (set it to 3.3V, or whatever the I/O
> voltage for the signal is).
>
> This way all driver use logical states, and the inversion is handled
> in
> DT.
>
Sensor power sequence as below:
------------------
| | |
| | |
dvdd/avdd/dovdd --------
---------
|
|
reset-pin -------------
In order to match this power sequece, "reset-pin" contrl flow is below:
1. config the "reset-pin" is "active-high" in DTS:
reset-gpios = <&pio 19 GPIO_ACTIVE_HIGH>;
2. image sensor driver probe function:
gc08a3->reset_gpio = devm_gpiod_get(dev, "reset",
GPIOD_OUT_LOW); //init "reset-pin" is low
3. image sensor driver power_on function:
gpiod_set_value_cansleep(gc08a3->reset_gpio, 1); //pull "reset-pin"
high
so, the expect state of "reset-pin" is from low to high.
If I am wrong, please correct me.
> > > > +usleep_range(GC08A3_MIN_SLEEP_US, GC08A3_MAX_SLEEP_US);
> > > > +
> > > > +return 0;
> > > > +}
>
> [snip]
>
> --
> Regards,
>
> Laurent Pinchart
