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Date: Wed, 23 Dec 2020 09:54:25 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Linux Media Mailing List <linux-media@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 07/12] media: uvcvideo: Implement UVC_EXT_GPIO_UNIT
Hi Ricardo,
On Tue, Dec 22, 2020 at 07:36:52PM +0100, Ricardo Ribalda wrote:
> On Tue, Dec 22, 2020 at 9:34 AM Laurent Pinchart wrote:
> > 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@...omium.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.
But the event will only be generated when the control is read, which the
process checking for events won't do (otherwise, it wouldn't need events
in the first place), and the process handling the video stream won't do
either. If the hardware can't generate events and polling is required,
I'm not sure trying to fake it would be useful.
> Also I think that is the way the v4l2-ctrl behaves.
v4l2-ctl is just a test tool, I'm more interested in real use cases :-)
> > > + 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
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