Re: [PATCH v5 07/12] media: uvcvideo: Implement UVC_EXT_GPIO_UNIT

Ricardo Ribalda
2020-12-22T18:37:47Z

Hi Laurent

Thanks for your review!

On Tue, Dec 22, 2020 at 9:34 AM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> On Mon, Dec 21, 2020 at 05:48:14PM +0100, Ricardo Ribalda wrote:
> > Some devices can implement a physical switch to disable the input of the
> > camera on demand. Think of it like an elegant privacy sticker.
> >
> > The system can read the status of the privacy switch via a GPIO.
> >
> > It is important to know the status of the switch, e.g. to notify the
> > user when the camera will produce black frames and a videochat
> > application is used.
> >
> > In some systems, the GPIO is connected to main SoC instead of the
> > camera controller, with the connected reported by the system firmware
>
> s/connected/connection/
>
> > (ACPI or DT). In that case, the UVC device isn't aware of the GPIO. We
> > need to implement a virtual entity to handle the GPIO fully on the
> > driver side.
> >
> > For example, for ACPI-based systems, the GPIO is reported in the USB
> > device object:
> >
> > Scope (\_SB.PCI0.XHCI.RHUB.HS07)
> > {
> >
> > /.../
> >
> > Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings
> > {
> > GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
> > "\\_SB.PCI0.GPIO", 0x00, ResourceConsumer, ,
> > )
> > { // Pin list
> > 0x0064
> > }
> > })
> > Name (_DSD, Package (0x02) // _DSD: Device-Specific Data
> > {
> > ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device Properties for _DSD */,
> > Package (0x01)
> > {
> > Package (0x02)
> > {
> > "privacy-gpio",
> > Package (0x04)
> > {
> > \_SB.PCI0.XHCI.RHUB.HS07,
> > Zero,
> > Zero,
> > One
> > }
> > }
> > }
> > })
> > }
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> > drivers/media/usb/uvc/uvc_ctrl.c | 7 ++
> > drivers/media/usb/uvc/uvc_driver.c | 156 +++++++++++++++++++++++++++++
> > drivers/media/usb/uvc/uvc_entity.c | 1 +
> > drivers/media/usb/uvc/uvcvideo.h | 16 +++
> > 4 files changed, 180 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index 528254230535..a430fa666897 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -1300,6 +1300,10 @@ static void __uvc_ctrl_status_event_work(struct uvc_device *dev,
> >
> > mutex_unlock(&chain->ctrl_mutex);
> >
> > + /* Events not started by the UVC device. E.g. the GPIO unit */
> > + if (!w->urb)
> > + return;
> > +
> > /* Resubmit the URB. */
> > w->urb->interval = dev->int_ep->desc.bInterval;
> > ret = usb_submit_urb(w->urb, GFP_KERNEL);
> > @@ -2317,6 +2321,9 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
> > } else if (UVC_ENTITY_TYPE(entity) == UVC_ITT_CAMERA) {
> > bmControls = entity->camera.bmControls;
> > bControlSize = entity->camera.bControlSize;
> > + } else if (UVC_ENTITY_TYPE(entity) == UVC_EXT_GPIO_UNIT) {
> > + bmControls = entity->gpio.bmControls;
> > + bControlSize = entity->gpio.bControlSize;
> > }
> >
> > /* Remove bogus/blacklisted controls */
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index c0c5f75ade40..72516101fdd0 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -7,6 +7,7 @@
> > */
> >
> > #include <linux/atomic.h>
> > +#include <linux/gpio/consumer.h>
> > #include <linux/kernel.h>
> > #include <linux/list.h>
> > #include <linux/module.h>
> > @@ -1020,6 +1021,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
> > }
> >
> > static const u8 uvc_camera_guid[16] = UVC_GUID_UVC_CAMERA;
> > +static const u8 uvc_gpio_guid[16] = UVC_GUID_EXT_GPIO_CONTROLLER;
> > static const u8 uvc_media_transport_input_guid[16] =
> > UVC_GUID_UVC_MEDIA_TRANSPORT_INPUT;
> > static const u8 uvc_processing_guid[16] = UVC_GUID_UVC_PROCESSING;
> > @@ -1051,6 +1053,9 @@ static struct uvc_entity *uvc_alloc_entity(u16 type, u16 id,
> > * is initialized by the caller.
> > */
> > switch (type) {
> > + case UVC_EXT_GPIO_UNIT:
> > + memcpy(entity->guid, uvc_gpio_guid, 16);
> > + break;
> > case UVC_ITT_CAMERA:
> > memcpy(entity->guid, uvc_camera_guid, 16);
> > break;
> > @@ -1464,6 +1469,137 @@ static int uvc_parse_control(struct uvc_device *dev)
> > return 0;
> > }
> >
> > +/* -----------------------------------------------------------------------------
> > + * Privacy GPIO
> > + */
> > +
> > +
> > +static u8 uvc_gpio_update_value(struct uvc_device *dev,
> > + struct uvc_entity *unit)
> > +{
> > + struct uvc_video_chain *chain;
> > + u8 gpio_val, old_val, new_val;
> > +
> > + gpio_val = new_val = gpiod_get_value_cansleep(unit->gpio.gpio_privacy);
> > +
> > + old_val = atomic_xchg(&unit->gpio.gpio_privacy_value, gpio_val);
> > + if (new_val == old_val)
> > + return new_val;
> > +
> > + /* GPIO entities are always on the first chain. */
> > + chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> > + uvc_ctrl_status_event(NULL, chain, unit->controls, &new_val);
> > +
> > + return 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;
> > +
> > + *(uint8_t *)data = uvc_gpio_update_value(dev, entity);
>
> s/uint8_t/u8/
>
> Do we really need to generate an event when the GPIO is read, if there's
> no IRQ support ?

I think so. Imagine a scenario where you have one process checking for
events and notifying the user about changes, and another process
handling the camera.
Also I think that is the way the v4l2-ctrl behaves.

>
> > + 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 struct uvc_entity *uvc_gpio_find_entity(struct uvc_device *dev)
> > +{
> > + struct uvc_video_chain *chain;
> > + struct uvc_entity *unit;
> > +
> > + /* GPIO entities are always on the first chain. */
> > + chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> > + list_for_each_entry(unit, &chain->entities, chain) {
> > + if (UVC_ENTITY_TYPE(unit) == UVC_EXT_GPIO_UNIT)
> > + return unit;
> > + }
>
> As there can only be a single GPIO entity, would it make sense to store
> a pointer to it in struct uvc_device to avoid walking the chain every
> time ?
>
> > +
> > + return NULL;
> > +}
> > +
> > +static irqreturn_t uvc_gpio_irq(int irq, void *data)
> > +{
> > + struct uvc_device *dev = data;
> > + struct uvc_entity *unit;
> > +
> > + unit = uvc_gpio_find_entity(dev);
> > + if (!unit)
> > + return IRQ_HANDLED;
> > +
> > + uvc_gpio_update_value(dev, unit);
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int uvc_gpio_parse(struct uvc_device *dev)
> > +{
> > + struct uvc_entity *unit;
> > + struct gpio_desc *gpio_privacy;
> > + int irq;
> > +
> > + gpio_privacy = devm_gpiod_get_optional(&dev->udev->dev, "privacy",
> > + GPIOD_IN);
> > + if (IS_ERR_OR_NULL(gpio_privacy))
> > + return PTR_ERR_OR_ZERO(gpio_privacy);
> > +
> > + unit = uvc_alloc_entity(UVC_EXT_GPIO_UNIT, UVC_EXT_GPIO_UNIT_ID, 0, 1);
> > + if (!unit)
> > + return -ENOMEM;
> > +
> > + irq = gpiod_to_irq(gpio_privacy);
> > + if (irq == -EPROBE_DEFER)
> > + return -EPROBE_DEFER;
> > +
> > + if (irq < 0)
> > + dev_warn(&dev->udev->dev,
> > + "Unable to find privacy_gpio: %d\n", irq);
>
> That's not right, the GPIO is found, it's only the IRQ that is
> unsupported.
>
> dev_warn(&dev->udev->dev,
> "No IRQ for privacy GPIO (%d)\n", irq);
>
> > +
> > + atomic_set(&unit->gpio.gpio_privacy_value, -1);
> > + unit->gpio.gpio_privacy = gpio_privacy;
> > + unit->gpio.irq = irq;
> > + 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;
> > +
> > + sprintf(unit->name, "GPIO");
>
> strncpy() would be simpler.
>
> > +
> > + list_add_tail(&unit->list, &dev->entities);
> > +
> > + return 0;
> > +}
> > +
> > +static int uvc_gpio_init_irq(struct uvc_device *dev)
> > +{
> > + int ret;
> > + struct uvc_entity *unit;
>
> Could you please swap those two lines ?
>
> > +
> > + unit = uvc_gpio_find_entity(dev);
> > + if (!unit)
> > + return 0;
> > +
> > + if (unit->gpio.irq < 0)
> > + return 0;
> > +
> > + ret = devm_request_threaded_irq(&dev->udev->dev, unit->gpio.irq, NULL,
> > + uvc_gpio_irq,
> > + IRQF_ONESHOT | IRQF_TRIGGER_FALLING |
> > + IRQF_TRIGGER_RISING,
>
> Extra space in the indentation.
>
> > + "uvc_privacy_gpio", dev);
> > + return ret;
>
> No need for a ret variable, you can write
>
> return devm_request_threaded_irq(...);
>
> (unless you want to move the error message here, see below).
>
> > +}
> > +
> > /* ------------------------------------------------------------------------
> > * UVC device scan
> > */
> > @@ -1915,6 +2051,7 @@ static int uvc_scan_device(struct uvc_device *dev)
> > {
> > struct uvc_video_chain *chain;
> > struct uvc_entity *term;
> > + struct uvc_entity *unit;
> >
> > list_for_each_entry(term, &dev->entities, list) {
> > if (!UVC_ENTITY_IS_OTERM(term))
> > @@ -1953,6 +2090,13 @@ static int uvc_scan_device(struct uvc_device *dev)
> > return -1;
> > }
> >
> > + /* Add GPIO entities to the first chain. */
> > + chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> > + list_for_each_entry(unit, &dev->entities, list) {
> > + if (UVC_ENTITY_TYPE(unit) == UVC_EXT_GPIO_UNIT)
> > + list_add_tail(&unit->chain, &chain->entities);
> > + }
> > +
> > return 0;
> > }
> >
> > @@ -2285,6 +2429,12 @@ static int uvc_probe(struct usb_interface *intf,
> > goto error;
> > }
> >
> > + /* Parse the associated GPIOs. */
> > + if (uvc_gpio_parse(dev) < 0) {
> > + uvc_trace(UVC_TRACE_PROBE, "Unable to parse UVC GPIOs\n");
> > + goto error;
> > + }
> > +
> > uvc_printk(KERN_INFO, "Found UVC %u.%02x device %s (%04x:%04x)\n",
> > dev->uvc_version >> 8, dev->uvc_version & 0xff,
> > udev->product ? udev->product : "<unnamed>",
> > @@ -2329,6 +2479,12 @@ static int uvc_probe(struct usb_interface *intf,
> > "supported.\n", ret);
> > }
> >
> > + ret = uvc_gpio_init_irq(dev);
> > + if (ret < 0)
> > + dev_warn(&dev->udev->dev,
> > + "Unable to request uvc_privacy_gpio irq %d. Continuing wihtout privacy events\n",
>
> s/uvc_privacy_gpio irq/privacy GPIO IRQ/ ?
>
> > + ret);
>
> This could be moved to uvc_gpio_init_irq(), up to you.
>
> > +
> > uvc_trace(UVC_TRACE_PROBE, "UVC device initialized.\n");
> > usb_enable_autosuspend(udev);
> > return 0;
> > diff --git a/drivers/media/usb/uvc/uvc_entity.c b/drivers/media/usb/uvc/uvc_entity.c
> > index ca3a9c2eec27..6a9ba5b498db 100644
> > --- a/drivers/media/usb/uvc/uvc_entity.c
> > +++ b/drivers/media/usb/uvc/uvc_entity.c
> > @@ -105,6 +105,7 @@ static int uvc_mc_init_entity(struct uvc_video_chain *chain,
> > case UVC_OTT_DISPLAY:
> > case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
> > case UVC_EXTERNAL_VENDOR_SPECIFIC:
> > + case UVC_EXT_GPIO_UNIT:
> > default:
> > function = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
> > break;
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index 6edbf79b2ff1..079a407ebba5 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -6,6 +6,7 @@
> > #error "The uvcvideo.h header is deprecated, use linux/uvcvideo.h instead."
> > #endif /* __KERNEL__ */
> >
> > +#include <linux/atomic.h>
> > #include <linux/kernel.h>
> > #include <linux/poll.h>
> > #include <linux/usb.h>
> > @@ -37,6 +38,8 @@
> > (UVC_ENTITY_IS_TERM(entity) && \
> > ((entity)->type & 0x8000) == UVC_TERM_OUTPUT)
> >
> > +#define UVC_EXT_GPIO_UNIT 0x7ffe
> > +#define UVC_EXT_GPIO_UNIT_ID 0x100
> >
> > /* ------------------------------------------------------------------------
> > * GUIDs
> > @@ -56,6 +59,9 @@
> > #define UVC_GUID_UVC_SELECTOR \
> > {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
> > 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02}
> > +#define UVC_GUID_EXT_GPIO_CONTROLLER \
> > + {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
> > + 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03}
> >
> > #define UVC_GUID_FORMAT_MJPEG \
> > { 'M', 'J', 'P', 'G', 0x00, 0x00, 0x10, 0x00, \
> > @@ -278,6 +284,8 @@ struct uvc_format_desc {
> > u32 fcc;
> > };
> >
> > +struct gpio_desc;
> > +
>
> This could be moved a bit up, with the other forward declaration.
>
> > /* The term 'entity' refers to both UVC units and UVC terminals.
> > *
> > * The type field is either the terminal type (wTerminalType in the terminal
> > @@ -353,6 +361,14 @@ struct uvc_entity {
> > u8 *bmControls;
> > u8 *bmControlsType;
> > } extension;
> > +
> > + struct {
> > + u8 bControlSize;
> > + u8 *bmControls;
> > + struct gpio_desc *gpio_privacy;
> > + int irq;
> > + atomic_t gpio_privacy_value;
> > + } gpio;
> > };
> >
> > u8 bNrInPins;
>
> --
> Regards,
>
> Laurent Pinchart

--
Ricardo Ribalda