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Date: Tue, 21 Nov 2023 21:46:42 +0100
From: Hans Verkuil <hverkuil-cisco@...all.nl>
To: Yunke Cao <yunkec@...omium.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Ricardo Ribalda <ribalda@...omium.org>
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
Sakari Ailus <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH RFC 3/3] media: uvcvideo: reimplement privacy GPIO as a
separate subdevice
Hi Yunke,
A comment below:
On 11/01/2023 09:52, Yunke Cao wrote:
> Reimplement privacy GPIO as a v4l2 subdev with a volatile privacy control.
> A v4l2 control event is sent in irq when privacy control value changes.
>
> The behavior matches the original implementation, except that the
> control is of a separate subdevice.
>
> V4L2 control kAPI is used for simplicity.
>
> Signed-off-by: Yunke Cao <yunkec@...omium.org>
> ---
> drivers/media/usb/uvc/uvc_driver.c | 44 +++-------------------
> drivers/media/usb/uvc/uvc_entity.c | 76 ++++++++++++++++++++++++++++++++++++++
> drivers/media/usb/uvc/uvcvideo.h | 19 +++++++---
> 3 files changed, 94 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index e4bcb5011360..25848f4dbce0 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1209,43 +1209,6 @@ static int uvc_parse_control(struct uvc_device *dev)
> * Privacy GPIO
> */
>
> -static void uvc_gpio_event(struct uvc_device *dev)
> -{
> - struct uvc_entity *unit = dev->gpio_unit;
> - struct uvc_video_chain *chain;
> - u8 new_val;
> -
> - if (!unit)
> - return;
> -
> - new_val = gpiod_get_value_cansleep(unit->gpio.gpio_privacy);
> -
> - /* GPIO entities are always on the first chain. */
> - chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> - uvc_ctrl_status_event(chain, unit->controls, &new_val);
> -}
> -
> -static int uvc_gpio_get_cur(struct uvc_device *dev, struct uvc_entity *entity,
> - u8 cs, void *data, u16 size)
> -{
> - if (cs != UVC_CT_PRIVACY_CONTROL || size < 1)
> - return -EINVAL;
> -
> - *(u8 *)data = gpiod_get_value_cansleep(entity->gpio.gpio_privacy);
> -
> - return 0;
> -}
> -
> -static int uvc_gpio_get_info(struct uvc_device *dev, struct uvc_entity *entity,
> - u8 cs, u8 *caps)
> -{
> - if (cs != UVC_CT_PRIVACY_CONTROL)
> - return -EINVAL;
> -
> - *caps = UVC_CONTROL_CAP_GET | UVC_CONTROL_CAP_AUTOUPDATE;
> - return 0;
> -}
> -
> static irqreturn_t uvc_gpio_irq(int irq, void *data)
> {
> struct uvc_device *dev = data;
> @@ -1279,8 +1242,6 @@ static int uvc_gpio_parse(struct uvc_device *dev)
> unit->gpio.bControlSize = 1;
> unit->gpio.bmControls = (u8 *)unit + sizeof(*unit);
> unit->gpio.bmControls[0] = 1;
> - unit->get_cur = uvc_gpio_get_cur;
> - unit->get_info = uvc_gpio_get_info;
> strscpy(unit->name, "GPIO", sizeof(unit->name));
>
> list_add_tail(&unit->list, &dev->entities);
> @@ -2202,6 +2163,11 @@ static int uvc_probe(struct usb_interface *intf,
> if (media_device_register(&dev->mdev) < 0)
> goto error;
> #endif
> +
> + /* Expose all subdev's nodes*/
> + if (v4l2_device_register_subdev_nodes(&dev->vdev) < 0)
> + goto error;
> +
> /* Save our data pointer in the interface data. */
> usb_set_intfdata(intf, dev);
>
> diff --git a/drivers/media/usb/uvc/uvc_entity.c b/drivers/media/usb/uvc/uvc_entity.c
> index 7c4d2f93d351..c8e41b42ffd8 100644
> --- a/drivers/media/usb/uvc/uvc_entity.c
> +++ b/drivers/media/usb/uvc/uvc_entity.c
> @@ -56,17 +56,90 @@ static int uvc_mc_create_links(struct uvc_video_chain *chain,
> return 0;
> }
>
> +static const struct v4l2_subdev_core_ops uvc_subdev_core_ops = {
> + .subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> + .unsubscribe_event = v4l2_event_subdev_unsubscribe,
> +};
> +
> static const struct v4l2_subdev_ops uvc_subdev_ops = {
> + .core = &uvc_subdev_core_ops,
> };
>
> void uvc_mc_cleanup_entity(struct uvc_entity *entity)
> {
> + if (UVC_ENTITY_TYPE(entity) == UVC_EXT_GPIO_UNIT)
> + v4l2_ctrl_handler_free(&entity->gpio.hdl);
> +
> if (UVC_ENTITY_TYPE(entity) != UVC_TT_STREAMING)
> media_entity_cleanup(&entity->subdev.entity);
> else if (entity->vdev != NULL)
> media_entity_cleanup(&entity->vdev->entity);
> }
>
> +static int uvc_gpio_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
> +{
> + struct uvc_gpio *gpio =
> + container_of(ctrl->handler, struct uvc_gpio, hdl);
> +
> + ctrl->cur.val = gpiod_get_value_cansleep(gpio->gpio_privacy);
> +
> + return 0;
> +}
> +
> +static const struct v4l2_ctrl_ops uvc_gpio_ctrl_ops = {
> + .g_volatile_ctrl = uvc_gpio_g_volatile_ctrl,
> +};
> +
> +void uvc_gpio_event(struct uvc_device *dev)
> +{
> + struct uvc_entity *unit = dev->gpio_unit;
> + struct v4l2_ctrl *ctrl;
> + struct v4l2_event ev;
> + s32 old_val;
> + int ret;
> +
> + if (!unit)
> + return;
> +
> + ctrl = unit->gpio.privacy_ctrl;
> + old_val = ctrl->cur.val;
> +
> + v4l2_ctrl_lock(ctrl);
> +
> + ret = uvc_gpio_g_volatile_ctrl(ctrl);
> + if (ret < 0 || old_val == ctrl->cur.val) {
> + v4l2_ctrl_unlock(ctrl);
> + return;
> + }
> +
> + v4l2_ctrl_fill_event(&ev, ctrl, V4L2_EVENT_CTRL_CH_VALUE);
> + v4l2_ctrl_unlock(ctrl);
> +
> + v4l2_event_queue(unit->subdev.devnode, &ev);
> +}
> +
> +static void uvc_gpio_init_ctrl(struct uvc_entity *entity)
> +{
> + struct v4l2_ctrl *ctrl;
> + struct v4l2_ctrl_handler *hdl = &entity->gpio.hdl;
> +
> + entity->subdev.flags = V4L2_SUBDEV_FL_HAS_DEVNODE |
> + V4L2_SUBDEV_FL_HAS_EVENTS;
> +
> + v4l2_ctrl_handler_init(hdl, 1);
> + entity->subdev.ctrl_handler = hdl;
> + ctrl = v4l2_ctrl_new_std(hdl, &uvc_gpio_ctrl_ops, V4L2_CID_PRIVACY,
> + 0, 1, 1, 0);
> + if (ctrl)
> + ctrl->flags |= V4L2_CTRL_FLAG_VOLATILE |
> + V4L2_CTRL_FLAG_READ_ONLY;
This is not a volatile control. You know exactly what the value is
and when it changes since a gpio interrupt is issued.
So this is just a regular read-only control, and when uvc_gpio_event
is called you can just call v4l2_ctrl_s_ctrl with the new value
from gpiod_get_value_cansleep().
No need to expose v4l2_ctrl_fill_event either since the call above
will take care of the control event.
Regards,
Hans
> +
> + /* Read GPIO value to initialize the control. */
> + uvc_gpio_g_volatile_ctrl(ctrl);
> +
> + entity->gpio.privacy_ctrl = ctrl;
> +}
> +
> static int uvc_mc_init_entity(struct uvc_video_chain *chain,
> struct uvc_entity *entity)
> {
> @@ -113,6 +186,9 @@ static int uvc_mc_init_entity(struct uvc_video_chain *chain,
>
> entity->subdev.entity.function = function;
>
> + if (UVC_ENTITY_TYPE(entity) == UVC_EXT_GPIO_UNIT)
> + uvc_gpio_init_ctrl(entity);
> +
> ret = media_entity_pads_init(&entity->subdev.entity,
> entity->num_pads, entity->pads);
>
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index df93db259312..19ca2896c398 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -15,6 +15,7 @@
> #include <linux/videodev2.h>
> #include <linux/workqueue.h>
> #include <media/media-device.h>
> +#include <media/v4l2-ctrls.h>
> #include <media/v4l2-device.h>
> #include <media/v4l2-event.h>
> #include <media/v4l2-fh.h>
> @@ -163,6 +164,15 @@ struct uvc_control {
>
> #define UVC_ENTITY_FLAG_DEFAULT (1 << 0)
>
> +struct uvc_gpio {
> + u8 bControlSize;
> + u8 *bmControls;
> + struct gpio_desc *gpio_privacy;
> + int irq;
> + struct v4l2_ctrl_handler hdl;
> + struct v4l2_ctrl *privacy_ctrl;
> +};
> +
> struct uvc_entity {
> struct list_head list; /* Entity as part of a UVC device. */
> struct list_head chain; /* Entity as part of a video device chain. */
> @@ -221,12 +231,7 @@ struct uvc_entity {
> u8 *bmControlsType;
> } extension;
>
> - struct {
> - u8 bControlSize;
> - u8 *bmControls;
> - struct gpio_desc *gpio_privacy;
> - int irq;
> - } gpio;
> + struct uvc_gpio gpio;
> };
>
> u8 bNrInPins;
> @@ -766,6 +771,8 @@ int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
> int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
> struct uvc_xu_control_query *xqry);
>
> +void uvc_gpio_event(struct uvc_device *dev);
> +
> /* Utility functions */
> struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts,
> u8 epaddr);
>
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