[libcamera-devel] [PATCH v5 1/4] libcamera: V4L2Device: Remove the controls order assumption in updateControls()

[Laurent Pinchart]

Hi Hiro,

Thank you for the patch.

On Fri, Apr 23, 2021 at 06:36:50PM +0900, Hirokazu Honda wrote:
> The original updateControls() has the assumption that ctrls and
> v4l2Ctrls lists are in the same order. It is dependent on the
> caller implementation though. This changes updateControls()
> implementation so that it works without the assumption.
> 
> Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> ---
>  src/libcamera/v4l2_device.cpp | 27 ++++++++-------------------
>  1 file changed, 8 insertions(+), 19 deletions(-)
> 
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index decd19ef..ce2860c4 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -179,12 +179,6 @@ ControlList V4L2Device::getControls(const std::vector<uint32_t> &ids)
>  
>  	ControlList ctrls{ controls_ };
>  
> -	/*
> -	 * Start by filling the ControlList. This can't be combined with filling
> -	 * v4l2Ctrls, as updateControls() relies on both containers having the
> -	 * same order, and the control list is based on a map, which is not
> -	 * sorted by insertion order.
> -	 */
>  	for (uint32_t id : ids) {
>  		const auto iter = controls_.find(id);
>  		if (iter == controls_.end()) {
> @@ -525,19 +519,14 @@ void V4L2Device::updateControls(ControlList *ctrls,
>  				const struct v4l2_ext_control *v4l2Ctrls,
>  				unsigned int count)
>  {
> -	unsigned int i = 0;
> -	for (auto &ctrl : *ctrls) {
> -		if (i == count)
> -			break;
> +	for (unsigned int i = 0; i < count; i++) {
> +		const struct v4l2_ext_control &v4l2Ctrl = v4l2Ctrls[i];
> +		const unsigned int id = v4l2Ctrl.id;

The main reason why we had a local id variable is because using
ctrl.first is not very readable. With this patch, we could use
v4l2Ctrl.id to replace id below. No need to change this though, a local
variable is fine.

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  
> -		const struct v4l2_ext_control *v4l2Ctrl = &v4l2Ctrls[i];
> -		unsigned int id = ctrl.first;
> -		ControlValue &value = ctrl.second;
> -
> -		const auto iter = controls_.find(id);
> -		switch (iter->first->type()) {
> +		ControlValue value = ctrls->get(id);
> +		switch (value.type()) {
>  		case ControlTypeInteger64:
> -			value.set<int64_t>(v4l2Ctrl->value64);
> +			value.set<int64_t>(v4l2Ctrl.value64);
>  			break;
>  
>  		case ControlTypeByte:
> @@ -552,11 +541,11 @@ void V4L2Device::updateControls(ControlList *ctrls,
>  			 * \todo To be changed when support for string controls
>  			 * will be added.
>  			 */
> -			value.set<int32_t>(v4l2Ctrl->value);
> +			value.set<int32_t>(v4l2Ctrl.value);
>  			break;
>  		}
>  
> -		i++;
> +		ctrls->set(id, value);
>  	}
>  }
>  

-- 
Regards,

Laurent Pinchart