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libcamera: v4l2_device: Simplify usage of getControls()

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The V4L2Device::getControls() function takes a ControlList that needs to
be pre-populated with dummy entries for the controls that need to be
read. This is a cumbersome API, especially when reading a single
control. Make it nicer by passing the list of V4L2 controls as a vector
of control IDs, and returning a ControlList.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
This commit is contained in:
Laurent Pinchart 2020-04-26 02:08:37 +03:00
parent d4680c8ca2
commit 79ab0e925a
5 changed files with 62 additions and 61 deletions
Download patch file Download diff file Expand all files Collapse all files

64
src/libcamera/v4l2_device.cpp
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@ -147,46 +147,51 @@ void V4L2Device::close()
/**
* \brief Read controls from the device
* \param[inout] ctrls The list of controls to read
* \param[in] ids The list of controls to read, specified by their ID
*
* This method reads the value of all controls contained in \a ctrls, and stores
* their values in the corresponding \a ctrls entry.
* This method reads the value of all controls contained in \a ids, and returns
* their values as a ControlList.
*
* If any control in \a ctrls is not supported by the device, is disabled (i.e.
* If any control in \a ids is not supported by the device, is disabled (i.e.
* has the V4L2_CTRL_FLAG_DISABLED flag set), or if any other error occurs
* during validation of the requested controls, no control is read and this
* method returns -EINVAL.
* method returns an empty control list.
*
* If an error occurs while reading the controls, the index of the first control
* that couldn't be read is returned. The value of all controls below that index
* are updated in \a ctrls, while the value of all the other controls are not
* changed.
*
* \return 0 on success or an error code otherwise
* \retval -EINVAL One of the control is not supported or not accessible
* \retval i The index of the control that failed
* \return The control values in a ControlList on success, or an empty list on
* error
*/
int V4L2Device::getControls(ControlList *ctrls)
ControlList V4L2Device::getControls(const std::vector<uint32_t> &ids)
{
unsigned int count = ctrls->size();
unsigned int count = ids.size();
if (count == 0)
return 0;
return {};
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()) {
LOG(V4L2, Error)
<< "Control " << utils::hex(id) << " not found";
return {};
}
ctrls.set(id, {});
}
struct v4l2_ext_control v4l2Ctrls[count];
memset(v4l2Ctrls, 0, sizeof(v4l2Ctrls));
unsigned int i = 0;
for (auto &ctrl : *ctrls) {
for (auto &ctrl : ctrls) {
unsigned int id = ctrl.first;
const auto iter = controls_.find(id);
if (iter == controls_.end()) {
LOG(V4L2, Error)
<< "Control " << utils::hex(id) << " not found";
return -EINVAL;
}
const struct v4l2_query_ext_ctrl &info = controlInfo_[id];
ControlValue &value = ctrl.second;
if (info.flags & V4L2_CTRL_FLAG_HAS_PAYLOAD) {
ControlType type;
@ -200,9 +205,10 @@ int V4L2Device::getControls(ControlList *ctrls)
LOG(V4L2, Error)
<< "Unsupported payload control type "
<< info.type;
return -EINVAL;
return {};
}
ControlValue &value = ctrl.second;
value.reserve(type, true, info.elems);
Span<uint8_t> data = value.data();
@ -227,7 +233,7 @@ int V4L2Device::getControls(ControlList *ctrls)
if (errorIdx == 0 || errorIdx >= count) {
LOG(V4L2, Error) << "Unable to read controls: "
<< strerror(-ret);
return -EINVAL;
return {};
}
/* A specific control failed. */
@ -237,9 +243,9 @@ int V4L2Device::getControls(ControlList *ctrls)
ret = errorIdx;
}
updateControls(ctrls, v4l2Ctrls, count);
updateControls(&ctrls, v4l2Ctrls, count);
return ret;
return ctrls;
}
/**