[media] uvcvideo: Send control change events for slave ctrls when the master changes

This allows v4l2 control UI-s to update the inactive state (ie grey-ing
out of controls) for slave controls when the master control changes.

[Use __uvc_find_control() to find slave controls, as they're always
located in the same entity as the corresponding master control]

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 56 insertions, 2 deletions

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index ae7371f3a39..03212c70333 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -1177,22 +1177,76 @@ static void uvc_ctrl_send_event(struct uvc_fh *handle,
 
         list_for_each_entry(sev, &mapping->ev_subs, node) {
                 if (sev->fh && (sev->fh != &handle->vfh ||
-                    (sev->flags & V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK)))
+                    (sev->flags & V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK) ||
+                    (changes & V4L2_EVENT_CTRL_CH_FLAGS)))
                         v4l2_event_queue_fh(sev->fh, &ev);
         }
 }
 
+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)
+{
+        struct uvc_control_mapping *mapping = NULL;
+        struct uvc_control *ctrl = NULL;
+        u32 changes = V4L2_EVENT_CTRL_CH_FLAGS;
+        unsigned int i;
+        s32 val = 0;
+
+        /*
+         * We can skip sending an event for the slave if the slave
+         * is being modified in the same transaction.
+         */
+        for (i = 0; i < xctrls_count; i++) {
+                if (xctrls[i].id == slave_id)
+                        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);
+}
+
 static void uvc_ctrl_send_events(struct uvc_fh *handle,
         const struct v4l2_ext_control *xctrls, unsigned int xctrls_count)
 {
         struct uvc_control_mapping *mapping;
         struct uvc_control *ctrl;
+        u32 changes = V4L2_EVENT_CTRL_CH_VALUE;
         unsigned int i;
+        unsigned int j;
 
         for (i = 0; i < xctrls_count; ++i) {
                 ctrl = uvc_find_control(handle->chain, xctrls[i].id, &mapping);
+
+                for (j = 0; j < ARRAY_SIZE(mapping->slave_ids); ++j) {
+                        if (!mapping->slave_ids[j])
+                                break;
+                        uvc_ctrl_send_slave_event(handle, ctrl,
+                                                  mapping->slave_ids[j],
+                                                  xctrls, xctrls_count);
+                }
+
+                /*
+                 * If the master is being modified in the same transaction
+                 * flags may change too.
+                 */
+                if (mapping->master_id) {
+                        for (j = 0; j < xctrls_count; j++) {
+                                if (xctrls[j].id == mapping->master_id) {
+                                        changes |= V4L2_EVENT_CTRL_CH_FLAGS;
+                                        break;
+                                }
+                        }
+                }
+
                 uvc_ctrl_send_event(handle, ctrl, mapping, xctrls[i].value,
-                                    V4L2_EVENT_CTRL_CH_VALUE);
+                                    changes);
         }
 }