[libcamera-devel] [PATCH v2 3/5] libcamera: delayed_controls: Remove unneeded write when starting up

[Naushir Patuck]

On DelayedControls::reset(), the values retrieved from the sensor device
were added to the queues with the updated flag set to true. This would
cause the helper to write out the value to the device again on the first
DelayedControls::applyControls() call. This is unnecessary, as the
controls written are identical to what is stored in the device driver.

Fix this by explicitly setting the update flag to false in
DelayedControls::reset() when adding the controls to the queue.

Additionally, use the Info() constructor when adding items to the queue
for consistency.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
Fixes: 3d4b7b005911 ("libcamera: delayed_controls: Add helper for controls that apply with a delay")
---
 include/libcamera/internal/delayed_controls.h |  4 ++--
 src/libcamera/delayed_controls.cpp            | 14 ++++++++------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/libcamera/internal/delayed_controls.h b/include/libcamera/internal/delayed_controls.h
index 564d9f2e2440..2a6a912bde10 100644
--- a/include/libcamera/internal/delayed_controls.h
+++ b/include/libcamera/internal/delayed_controls.h
@@ -43,8 +43,8 @@ private:
 		{
 		}
 
-		Info(const ControlValue &v)
-			: ControlValue(v), updated(true)
+		Info(const ControlValue &v, bool updated_ = true)
+			: ControlValue(v), updated(updated_)
 		{
 		}
 
diff --git a/src/libcamera/delayed_controls.cpp b/src/libcamera/delayed_controls.cpp
index 3ed1dfebd035..21dc3e164fe9 100644
--- a/src/libcamera/delayed_controls.cpp
+++ b/src/libcamera/delayed_controls.cpp
@@ -111,7 +111,11 @@ void DelayedControls::reset()
 	values_.clear();
 	for (const auto &ctrl : controls) {
 		const ControlId *id = device_->controls().idmap().at(ctrl.first);
-		values_[id][0] = Info(ctrl.second);
+		/*
+		 * Do not mark this control value as updated, it does not need
+		 * to be written to to device on startup.
+		 */
+		values_[id][0] = Info(ctrl.second, false);
 	}
 }
 
@@ -126,11 +130,10 @@ void DelayedControls::reset()
  */
 bool DelayedControls::push(const ControlList &controls)
 {
-	/* Copy state from previous frame. */
+	/* Copy state from previous frame and clear the updated flag */
 	for (auto &ctrl : values_) {
 		Info &info = ctrl.second[queueCount_];
-		info = values_[ctrl.first][queueCount_ - 1];
-		info.updated = false;
+		info = Info(values_[ctrl.first][queueCount_ - 1], false);
 	}
 
 	/* Update with new controls. */
@@ -150,8 +153,7 @@ bool DelayedControls::push(const ControlList &controls)
 
 		Info &info = values_[id][queueCount_];
 
-		info = control.second;
-		info.updated = true;
+		info = Info(control.second);
 
 		LOG(DelayedControls, Debug)
 			<< "Queuing " << id->name()
-- 
2.25.1