Hi Laurent,
Thanks for the review.
On Thu, 12 Jul 2018, Laurent Pinchart wrote:
> Hi Guennadi,
>
> Thank you for the patch.
>
> On Tuesday, 8 May 2018 18:07:43 EEST Guennadi Liakhovetski wrote:
> > UVC defines a method of handling asynchronous controls, which sends a
> > USB packet over the interrupt pipe. This patch implements support for
> > such packets by sending a control event to the user. Since this can
> > involve USB traffic and, therefore, scheduling, this has to be done
> > in a work queue.
> >
> > Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxx>
> > ---
> >
> > v8:
> >
> > * avoid losing events by delaying the status URB resubmission until
> > after completion of the current event
> > * extract control value calculation into __uvc_ctrl_get_value()
> > * do not proactively return EBUSY if the previous control hasn't
> > completed yet, let the camera handle such cases
> > * multiple cosmetic changes
> >
> > drivers/media/usb/uvc/uvc_ctrl.c | 166 +++++++++++++++++++++++++++-------
> > drivers/media/usb/uvc/uvc_status.c | 112 ++++++++++++++++++++++---
> > drivers/media/usb/uvc/uvc_v4l2.c | 4 +-
> > drivers/media/usb/uvc/uvcvideo.h | 15 +++-
> > include/uapi/linux/uvcvideo.h | 2 +
> > 5 files changed, 255 insertions(+), 44 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c
> > b/drivers/media/usb/uvc/uvc_ctrl.c index 2a213c8..796f86a 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
[snip]
> > +static void uvc_ctrl_status_event_work(struct work_struct *work)
> > +{
> > + struct uvc_device *dev = container_of(work, struct uvc_device,
> > + async_ctrl.work);
> > + struct uvc_ctrl_work *w = &dev->async_ctrl;
> > + struct uvc_control_mapping *mapping;
> > + struct uvc_control *ctrl = w->ctrl;
> > + unsigned int i;
> > + int ret;
> > +
> > + mutex_lock(&w->chain->ctrl_mutex);
> > +
> > + list_for_each_entry(mapping, &ctrl->info.mappings, list) {
> > + s32 value = __uvc_ctrl_get_value(mapping, w->data);
> > +
> > + /*
> > + * So far none of the auto-update controls in the uvc_ctrls[]
> > + * table is mapped to a V4L control with slaves in the
> > + * uvc_ctrl_mappings[] list, so slave controls so far never have
> > + * handle == NULL, but this can change in the future
> > + */
> > + for (i = 0; i < ARRAY_SIZE(mapping->slave_ids); ++i) {
> > + if (!mapping->slave_ids[i])
> > + break;
> > +
> > + __uvc_ctrl_send_slave_event(ctrl->handle, w->chain,
> > + ctrl, mapping->slave_ids[i]);
> > + }
> > +
> > + uvc_ctrl_send_event(ctrl->handle, ctrl, mapping, value,
> > + V4L2_EVENT_CTRL_CH_VALUE);
> > + }
> > +
> > + mutex_unlock(&w->chain->ctrl_mutex);
> > +
> > + ctrl->handle = NULL;
>
> Can't this race with a uvc_ctrl_set() call, resulting in ctrl->handle being
> NULL after the control gets set ?
Right, it's better to set .handle to NULL before sending events. Something
like
mutex_lock();
handle = ctrl->handle;
ctrl->handle = NULL;
list_for_each_entry() {
...
uvc_ctrl_send_event(handle,...);
}
mutex_unlock();
?
>
> > + /* Resubmit the URB. */
> > + w->urb->interval = dev->int_ep->desc.bInterval;
> > + ret = usb_submit_urb(w->urb, GFP_KERNEL);
> > + if (ret < 0)
> > + uvc_printk(KERN_ERR, "Failed to resubmit status URB (%d).\n",
> > + ret);
> > +}
> > +
> > +bool uvc_ctrl_status_event(struct urb *urb, struct uvc_video_chain *chain,
> > + struct uvc_control *ctrl, const u8 *data)
> > +{
> > + struct uvc_device *dev = chain->dev;
> > + struct uvc_ctrl_work *w = &dev->async_ctrl;
> > +
> > + if (list_empty(&ctrl->info.mappings)) {
> > + ctrl->handle = NULL;
> > + return false;
> > + }
> > +
> > + w->data = data;
> > + w->urb = urb;
> > + w->chain = chain;
> > + w->ctrl = ctrl;
> > +
> > + schedule_work(&w->work);
> > +
> > + return true;
> > +}
> > +
> > +static void uvc_ctrl_send_slave_event(struct uvc_fh *handle,
> > + struct uvc_control *master, u32 slave_id,
> > + const struct v4l2_ext_control *xctrls, unsigned int xctrls_count)
> > +{
> > + unsigned int i;
> > +
> > /*
> > * We can skip sending an event for the slave if the slave
> > * is being modified in the same transaction.
> > @@ -1255,14 +1355,8 @@ static void uvc_ctrl_send_slave_event(struct uvc_fh
> > *handle, return;
> > }
> >
> > - __uvc_find_control(master->entity, slave_id, &mapping, &ctrl, 0);
> > - if (ctrl == NULL)
> > - return;
> > -
> > - if (__uvc_ctrl_get(handle->chain, ctrl, mapping, &val) == 0)
> > - changes |= V4L2_EVENT_CTRL_CH_VALUE;
> > -
> > - uvc_ctrl_send_event(handle, ctrl, mapping, val, changes);
> > + /* handle != NULL */
> > + __uvc_ctrl_send_slave_event(handle, NULL, master, slave_id);
> > }
> >
> > static void uvc_ctrl_send_events(struct uvc_fh *handle,
> > @@ -1277,6 +1371,10 @@ static void uvc_ctrl_send_events(struct uvc_fh
> > *handle, for (i = 0; i < xctrls_count; ++i) {
> > ctrl = uvc_find_control(handle->chain, xctrls[i].id, &mapping);
> >
> > + if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS)
> > + /* Notification will be sent from an Interrupt event. */
> > + continue;
> > +
> > for (j = 0; j < ARRAY_SIZE(mapping->slave_ids); ++j) {
> > if (!mapping->slave_ids[j])
> > break;
> > @@ -1472,9 +1570,10 @@ int uvc_ctrl_get(struct uvc_video_chain *chain,
> > return __uvc_ctrl_get(chain, ctrl, mapping, &xctrl->value);
> > }
> >
> > -int uvc_ctrl_set(struct uvc_video_chain *chain,
> > +int uvc_ctrl_set(struct uvc_fh *handle,
> > struct v4l2_ext_control *xctrl)
> > {
> > + struct uvc_video_chain *chain = handle->chain;
> > struct uvc_control *ctrl;
> > struct uvc_control_mapping *mapping;
> > s32 value;
> > @@ -1581,6 +1680,9 @@ int uvc_ctrl_set(struct uvc_video_chain *chain,
> > mapping->set(mapping, value,
> > uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
> >
> > + if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS)
> > + ctrl->handle = handle;
> > +
> > ctrl->dirty = 1;
> > ctrl->modified = 1;
> > return 0;
> > @@ -1612,7 +1714,9 @@ static int uvc_ctrl_get_flags(struct uvc_device *dev,
> >
> > | (data[0] & UVC_CONTROL_CAP_SET ?
> >
> > UVC_CTRL_FLAG_SET_CUR : 0)
> >
> > | (data[0] & UVC_CONTROL_CAP_AUTOUPDATE ?
> >
> > - UVC_CTRL_FLAG_AUTO_UPDATE : 0);
> > + UVC_CTRL_FLAG_AUTO_UPDATE : 0)
> > + | (data[0] & UVC_CONTROL_CAP_ASYNCHRONOUS ?
> > + UVC_CTRL_FLAG_ASYNCHRONOUS : 0);
> >
> > kfree(data);
> > return ret;
> > @@ -2173,6 +2277,8 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
> > struct uvc_entity *entity;
> > unsigned int i;
> >
> > + INIT_WORK(&dev->async_ctrl.work, uvc_ctrl_status_event_work);
> > +
> > /* Walk the entities list and instantiate controls */
> > list_for_each_entry(entity, &dev->entities, list) {
> > struct uvc_control *ctrl;
> > @@ -2241,6 +2347,8 @@ void uvc_ctrl_cleanup_device(struct uvc_device *dev)
> > struct uvc_entity *entity;
> > unsigned int i;
> >
> > + cancel_work_sync(&dev->async_ctrl.work);
> > +
> > /* Free controls and control mappings for all entities. */
> > list_for_each_entry(entity, &dev->entities, list) {
> > for (i = 0; i < entity->ncontrols; ++i) {
> > diff --git a/drivers/media/usb/uvc/uvc_status.c
> > b/drivers/media/usb/uvc/uvc_status.c index 7b71041..a0f2fea 100644
> > --- a/drivers/media/usb/uvc/uvc_status.c
> > +++ b/drivers/media/usb/uvc/uvc_status.c
> > @@ -78,7 +78,24 @@ static void uvc_input_report_key(struct uvc_device *dev,
> > unsigned int code, /*
> > --------------------------------------------------------------------------
> > * Status interrupt endpoint
> > */
> > -static void uvc_event_streaming(struct uvc_device *dev, u8 *data, int len)
> > +struct uvc_streaming_status {
> > + u8 bStatusType;
> > + u8 bOriginator;
> > + u8 bEvent;
> > + u8 bValue[];
> > +} __packed;
> > +
> > +struct uvc_control_status {
> > + u8 bStatusType;
> > + u8 bOriginator;
> > + u8 bEvent;
> > + u8 bSelector;
> > + u8 bAttribute;
> > + u8 bValue[];
> > +} __packed;
> > +
> > +static void uvc_event_streaming(struct uvc_device *dev,
> > + struct uvc_streaming_status *status, int len)
> > {
> > if (len < 3) {
> > uvc_trace(UVC_TRACE_STATUS, "Invalid streaming status event "
> > @@ -86,31 +103,98 @@ static void uvc_event_streaming(struct uvc_device *dev,
> > u8 *data, int len) return;
> > }
> >
> > - if (data[2] == 0) {
> > + if (status->bEvent == 0) {
> > if (len < 4)
> > return;
> > uvc_trace(UVC_TRACE_STATUS, "Button (intf %u) %s len %d\n",
> > - data[1], data[3] ? "pressed" : "released", len);
> > - uvc_input_report_key(dev, KEY_CAMERA, data[3]);
> > + status->bOriginator,
> > + status->bValue[0] ? "pressed" : "released", len);
> > + uvc_input_report_key(dev, KEY_CAMERA, status->bValue[0]);
> > } else {
> > uvc_trace(UVC_TRACE_STATUS,
> > "Stream %u error event %02x len %d.\n",
> > - data[1], data[2], len);
> > + status->bOriginator, status->bEvent, len);
> > }
> > }
> >
> > -static void uvc_event_control(struct uvc_device *dev, u8 *data, int len)
> > +#define UVC_CTRL_VALUE_CHANGE 0
> > +#define UVC_CTRL_INFO_CHANGE 1
> > +#define UVC_CTRL_FAILURE_CHANGE 2
> > +#define UVC_CTRL_MIN_CHANGE 3
> > +#define UVC_CTRL_MAX_CHANGE 4
> > +
> > +static struct uvc_control *uvc_event_entity_find_ctrl(struct uvc_entity
> > *entity, + u8 selector)
> > {
> > - char *attrs[3] = { "value", "info", "failure" };
> > + struct uvc_control *ctrl;
> > + unsigned int i;
> > +
> > + for (i = 0, ctrl = entity->controls; i < entity->ncontrols; i++, ctrl++)
> > + if (ctrl->info.selector == selector)
> > + return ctrl;
> >
> > - if (len < 6 || data[2] != 0 || data[4] > 2) {
> > + return NULL;
> > +}
> > +
> > +static struct uvc_control *uvc_event_find_ctrl(struct uvc_device *dev,
> > + const struct uvc_control_status *status,
> > + struct uvc_video_chain **chain)
> > +{
> > + list_for_each_entry((*chain), &dev->chains, list) {
> > + struct uvc_entity *entity;
> > + struct uvc_control *ctrl;
> > +
> > + list_for_each_entry(entity, &(*chain)->entities, chain) {
> > + if (entity->id != status->bOriginator)
> > + continue;
> > +
> > + ctrl = uvc_event_entity_find_ctrl(entity,
> > + status->bSelector);
> > + if (ctrl && (!ctrl->handle ||
> > + ctrl->handle->chain == *chain))
>
> I'm afraid I still don't understand why you need the chain check :-( Unless
> I'm mistaken, ctrl->handle is set in uvc_ctrl_set(), where the control is
> looked up from the chain corresponding to handle->chain. How can the check be
> false here ?
I think you're right, the bOriginator check should be enough.
>
> Those are my two major concerns. Apart from that I have other small concerns
> that I propose addressing myself to avoid further delays. I've been slow
> enough when it comes to reviewing this series, if we can clear the two issues
> above, I'll handle the rest.
Once I get your review of patch #3, I'll fix these two issues and
resubmit, so you can also tell me your "minor concerns," since I'll be
resubmitting anyway.
Thanks
Guennadi
>
> > + return ctrl;
> > + }
> > + }
> > +
> > + return NULL;
> > +}
> > +
> > +static bool uvc_event_control(struct urb *urb,
> > + const struct uvc_control_status *status, int len)
> > +{
> > + static const char *attrs[] = { "value", "info", "failure", "min", "max" };
> > + struct uvc_device *dev = urb->context;
> > + struct uvc_video_chain *chain;
> > + struct uvc_control *ctrl;
> > +
> > + if (len < 6 || status->bEvent != 0 ||
> > + status->bAttribute >= ARRAY_SIZE(attrs)) {
> > uvc_trace(UVC_TRACE_STATUS, "Invalid control status event "
> > "received.\n");
> > - return;
> > + return false;
> > }
> >
> > uvc_trace(UVC_TRACE_STATUS, "Control %u/%u %s change len %d.\n",
> > - data[1], data[3], attrs[data[4]], len);
> > + status->bOriginator, status->bSelector,
> > + attrs[status->bAttribute], len);
> > +
> > + /* Find the control. */
> > + ctrl = uvc_event_find_ctrl(dev, status, &chain);
> > + if (!ctrl)
> > + return false;
> > +
> > + switch (status->bAttribute) {
> > + case UVC_CTRL_VALUE_CHANGE:
> > + return uvc_ctrl_status_event(urb, chain, ctrl, status->bValue);
> > +
> > + case UVC_CTRL_INFO_CHANGE:
> > + case UVC_CTRL_FAILURE_CHANGE:
> > + case UVC_CTRL_MIN_CHANGE:
> > + case UVC_CTRL_MAX_CHANGE:
> > + break;
> > + }
> > +
> > + return false;
> > }
> >
> > static void uvc_status_complete(struct urb *urb)
> > @@ -139,11 +223,15 @@ static void uvc_status_complete(struct urb *urb)
> > if (len > 0) {
> > switch (dev->status[0] & 0x0f) {
> > case UVC_STATUS_TYPE_CONTROL:
> > - uvc_event_control(dev, dev->status, len);
> > + if (uvc_event_control(urb,
> > + (struct uvc_control_status *)dev->status, len))
> > + /* The URB will be resubmitted in work context */
> > + return;
> > break;
> >
> > case UVC_STATUS_TYPE_STREAMING:
> > - uvc_event_streaming(dev, dev->status, len);
> > + uvc_event_streaming(dev,
> > + (struct uvc_streaming_status *)dev->status, len);
> > break;
> >
> > default:
> > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c
> > b/drivers/media/usb/uvc/uvc_v4l2.c index bd32914..18a7384 100644
> > --- a/drivers/media/usb/uvc/uvc_v4l2.c
> > +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> > @@ -994,7 +994,7 @@ static int uvc_ioctl_s_ctrl(struct file *file, void *fh,
> > if (ret < 0)
> > return ret;
> >
> > - ret = uvc_ctrl_set(chain, &xctrl);
> > + ret = uvc_ctrl_set(handle, &xctrl);
> > if (ret < 0) {
> > uvc_ctrl_rollback(handle);
> > return ret;
> > @@ -1069,7 +1069,7 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh
> > *handle, return ret;
> >
> > for (i = 0; i < ctrls->count; ++ctrl, ++i) {
> > - ret = uvc_ctrl_set(chain, ctrl);
> > + ret = uvc_ctrl_set(handle, ctrl);
> > if (ret < 0) {
> > uvc_ctrl_rollback(handle);
> > ctrls->error_idx = commit ? ctrls->count : i;
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h
> > b/drivers/media/usb/uvc/uvcvideo.h index be5cf17..0e5e920 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -12,6 +12,7 @@
> > #include <linux/usb/video.h>
> > #include <linux/uvcvideo.h>
> > #include <linux/videodev2.h>
> > +#include <linux/workqueue.h>
> > #include <media/media-device.h>
> > #include <media/v4l2-device.h>
> > #include <media/v4l2-event.h>
> > @@ -256,6 +257,8 @@ struct uvc_control {
> > initialized:1;
> >
> > u8 *uvc_data;
> > +
> > + struct uvc_fh *handle; /* Used for asynchronous event delivery */
> > };
> >
> > struct uvc_format_desc {
> > @@ -600,6 +603,14 @@ struct uvc_device {
> > u8 *status;
> > struct input_dev *input;
> > char input_phys[64];
> > +
> > + struct uvc_ctrl_work {
> > + struct work_struct work;
> > + struct urb *urb;
> > + struct uvc_video_chain *chain;
> > + struct uvc_control *ctrl;
> > + const void *data;
> > + } async_ctrl;
> > };
> >
> > enum uvc_handle_state {
> > @@ -753,6 +764,8 @@ int uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
> > int uvc_ctrl_init_device(struct uvc_device *dev);
> > void uvc_ctrl_cleanup_device(struct uvc_device *dev);
> > int uvc_ctrl_restore_values(struct uvc_device *dev);
> > +bool uvc_ctrl_status_event(struct urb *urb, struct uvc_video_chain *chain,
> > + struct uvc_control *ctrl, const u8 *data);
> >
> > int uvc_ctrl_begin(struct uvc_video_chain *chain);
> > int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
> > @@ -770,7 +783,7 @@ static inline int uvc_ctrl_rollback(struct uvc_fh
> > *handle) }
> >
> > int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control
> > *xctrl); -int uvc_ctrl_set(struct uvc_video_chain *chain, struct
> > v4l2_ext_control *xctrl); +int uvc_ctrl_set(struct uvc_fh *handle, struct
> > v4l2_ext_control *xctrl);
> >
> > int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
> > struct uvc_xu_control_query *xqry);
> > diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h
> > index 020714d..f80f05b 100644
> > --- a/include/uapi/linux/uvcvideo.h
> > +++ b/include/uapi/linux/uvcvideo.h
> > @@ -28,6 +28,8 @@
> > #define UVC_CTRL_FLAG_RESTORE (1 << 6)
> > /* Control can be updated by the camera. */
> > #define UVC_CTRL_FLAG_AUTO_UPDATE (1 << 7)
> > +/* Control supports asynchronous reporting */
> > +#define UVC_CTRL_FLAG_ASYNCHRONOUS (1 << 8)
> >
> > #define UVC_CTRL_FLAG_GET_RANGE \
> > (UVC_CTRL_FLAG_GET_CUR | UVC_CTRL_FLAG_GET_MIN | \
>
>
> --
> Regards,
>
> Laurent Pinchart
>
>
>
