Re: [PATCH v2 3/5] media: atomisp: gc0310: Turn into standard v4l2 sensor driver

[Jacopo Mondi <jacopo.mondi@ideasonboard.com>]

Hi Sakari, Hans

On Wed, Jul 05, 2023 at 01:45:30PM +0000, Sakari Ailus wrote:
> Hi Hans,
>
> On Thu, May 25, 2023 at 09:00:58PM +0200, Hans de Goede wrote:
> > Switch the atomisp-gc0310 driver to v4l2 async device registration.
> >
> > After this change this driver no longer depends on
> > atomisp_gmin_platform and all atomisp-isms are gone.
> >
> > Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> > ---
> > Changes in v2:
> > - Drop v4l2_get_acpi_sensor_info() call in this patch
> > - Wait for fwnode graph endpoint so that the bridge's ACPI
> >   parsing gets a chance to register the GPIO mappings
> >   before probing the sensor
> > - Switch to endpoint matching
> > ---
> >  .../media/atomisp/i2c/atomisp-gc0310.c        | 29 ++++++++++++-------
> >  .../media/atomisp/pci/atomisp_csi2_bridge.c   |  2 ++
> >  2 files changed, 20 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/staging/media/atomisp/i2c/atomisp-gc0310.c b/drivers/staging/media/atomisp/i2c/atomisp-gc0310.c
> > index 1829ba419e3e..9a11793f34f7 100644
> > --- a/drivers/staging/media/atomisp/i2c/atomisp-gc0310.c
> > +++ b/drivers/staging/media/atomisp/i2c/atomisp-gc0310.c
> > @@ -29,8 +29,6 @@
> >  #include <media/v4l2-ctrls.h>
> >  #include <media/v4l2-device.h>
> >
> > -#include "../include/linux/atomisp_gmin_platform.h"
> > -
> >  #define GC0310_NATIVE_WIDTH			656
> >  #define GC0310_NATIVE_HEIGHT			496
> >
> > @@ -85,6 +83,7 @@ struct gc0310_device {
> >  	struct mutex input_lock;
> >  	bool is_streaming;
> >
> > +	struct fwnode_handle *ep_fwnode;
> >  	struct gpio_desc *reset;
> >  	struct gpio_desc *powerdown;
> >
> > @@ -596,11 +595,11 @@ static void gc0310_remove(struct i2c_client *client)
> >
> >  	dev_dbg(&client->dev, "gc0310_remove...\n");
> >
> > -	atomisp_unregister_subdev(sd);
> > -	v4l2_device_unregister_subdev(sd);
> > +	v4l2_async_unregister_subdev(sd);
> >  	media_entity_cleanup(&dev->sd.entity);
> >  	v4l2_ctrl_handler_free(&dev->ctrls.handler);
> >  	mutex_destroy(&dev->input_lock);
> > +	fwnode_handle_put(dev->ep_fwnode);
> >  	pm_runtime_disable(&client->dev);
> >  }
> >
> > @@ -613,19 +612,27 @@ static int gc0310_probe(struct i2c_client *client)
> >  	if (!dev)
> >  		return -ENOMEM;
> >
> > -	ret = v4l2_get_acpi_sensor_info(&client->dev, NULL);
> > -	if (ret)
> > -		return ret;
> > +	/*
> > +	 * Sometimes the fwnode graph is initialized by the bridge driver.
> > +	 * Bridge drivers doing this may also add GPIO mappings, wait for this.
> > +	 */
> > +	dev->ep_fwnode = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev), NULL);
> > +	if (!dev->ep_fwnode)
> > +		return dev_err_probe(&client->dev, -EPROBE_DEFER, "waiting for fwnode graph endpoint\n");
> >
> >  	dev->reset = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_HIGH);
> > -	if (IS_ERR(dev->reset))
> > +	if (IS_ERR(dev->reset)) {
> > +		fwnode_handle_put(dev->ep_fwnode);
> >  		return dev_err_probe(&client->dev, PTR_ERR(dev->reset),
> >  				     "getting reset GPIO\n");
> > +	}
> >
> >  	dev->powerdown = devm_gpiod_get(&client->dev, "powerdown", GPIOD_OUT_HIGH);
> > -	if (IS_ERR(dev->powerdown))
> > +	if (IS_ERR(dev->powerdown)) {
> > +		fwnode_handle_put(dev->ep_fwnode);
> >  		return dev_err_probe(&client->dev, PTR_ERR(dev->powerdown),
> >  				     "getting powerdown GPIO\n");
> > +	}
> >
> >  	mutex_init(&dev->input_lock);
> >  	v4l2_i2c_subdev_init(&dev->sd, client, &gc0310_ops);
> > @@ -645,6 +652,7 @@ static int gc0310_probe(struct i2c_client *client)
> >  	dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> >  	dev->pad.flags = MEDIA_PAD_FL_SOURCE;
> >  	dev->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> > +	dev->sd.fwnode = dev->ep_fwnode;
>
> Same for this one: leave as-is --- the v4l2_async_register_subdev()
> function will set the device fwnode for this.
>
> >
> >  	ret = gc0310_init_controls(dev);
> >  	if (ret) {
> > @@ -658,8 +666,7 @@ static int gc0310_probe(struct i2c_client *client)
> >  		return ret;
> >  	}
>
> This driver should (as well as ov2680) check for the link frequencies. This
> is an old sensor so if all users eventually use this via firmware that
> lacks this information, there's little benefit for adding the code. But
> otherwise this is seen as a bug.
>
> <URL:https://hverkuil.home.xs4all.nl/spec/driver-api/camera-sensor.html#handling-clocks
>
> The raw cameras should use pixel rate and blanking controls for configuring
> the frame interval. This one uses s_frame_interval instead, and it may be
> difficult to find the information needed for the pixel rate based API.
>
> Cc Jacopo.

Thanks

If you intend to use these devices with libcamera be aware we mandate
support for the following controls

V4L2_CID_ANALOGUE_GAIN
V4L2_CID_EXPOSURE
V4L2_CID_HBLANK
V4L2_CID_PIXEL_RATE
V4L2_CID_VBLANK

https://git.libcamera.org/libcamera/libcamera.git/tree/Documentation/sensor_driver_requirements.rst#n20

Do you think it would be possible to at least expose them read-only ?
This -should- be ok for libcamera. Your s_frame_interval() calls then
need to update the value of the controls.

Thanks
   j

>
> >
> > -	ret = atomisp_register_sensor_no_gmin(&dev->sd, 1, ATOMISP_INPUT_FORMAT_RAW_8,
> > -					      atomisp_bayer_order_grbg);
> > +	ret = v4l2_async_register_subdev_sensor(&dev->sd);
> >  	if (ret) {
> >  		gc0310_remove(client);
> >  		return ret;
> > diff --git a/drivers/staging/media/atomisp/pci/atomisp_csi2_bridge.c b/drivers/staging/media/atomisp/pci/atomisp_csi2_bridge.c
> > index d7d9cac2c3b8..5268a0d25051 100644
> > --- a/drivers/staging/media/atomisp/pci/atomisp_csi2_bridge.c
> > +++ b/drivers/staging/media/atomisp/pci/atomisp_csi2_bridge.c
> > @@ -89,6 +89,8 @@ static const guid_t atomisp_dsm_guid =
> >   * power-management and with v4l2-async probing.
> >   */
> >  static const struct atomisp_csi2_sensor_config supported_sensors[] = {
> > +	/* GalaxyCore GC0310 */
> > +	{ "INT0310", 1 },
> >  	/* Omnivision OV2680 */
> >  	{ "OVTI2680", 1 },
> >  };
>
> --
> Kind regards,
>
> Sakari Ailus