[libcamera-devel] [PATCH] libcamera: V4L2Device: Fix a type mismatch of ControlValue

[Jacopo Mondi]

Hi Hiro,

On Tue, May 25, 2021 at 02:33:41PM +0900, Hirokazu Honda wrote:
> The commit (34bee5e8) of removing the controls order assumption

We usually spell the commit message out as:

Commit 34bee5e84ecb ("libcamera: V4L2Device: Remove the controls order
assumption in updateControls()") removed the control odering
assumption without changing the updateControls() function accordingly.

> doesn't change the update ControlValue type in
> V4L2Device::updateControls(). However, this is wrong because the
> ControlValue is set to a placeholder ControlValue in
> V4L2Device::getControls(), so the type is ControlTypeNone.
> We should rather look up the type in V4L2Device::controls_ with a
> specified id.

>
> Fixes: 34bee5e8 (libcamera: V4L2Device: Remove the controls order assumption in updateControls())
> Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> ---
>  src/libcamera/v4l2_device.cpp | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index 7f7e5b8f..cc4f52bf 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -621,7 +621,11 @@ void V4L2Device::updateControls(ControlList *ctrls,
>  		const unsigned int id = v4l2Ctrl.id;
>
>  		ControlValue value = ctrls->get(id);

I've just noticed we do

                ControlValue value = ctrls.get()
                switch() {
                        value.set();
                }
                ctrls.set(id, value);

Can't we just take a reference and modify value ?
(not related to this patch though).

> -		switch (value.type()) {
> +
> +		auto iter = controls_.find(id);

const auto & ?

> +		ASSERT(iter != controls_.end());
> +		const ControlType type = iter->first->type();
> +		switch (type) {

You could save the local variable if you want to

>  		case ControlTypeInteger64:
>  			value.set<int64_t>(v4l2Ctrl.value64);
>  			break;
> --
> 2.31.1.818.g46aad6cb9e-goog
>