[libcamera-devel] [PATCH 1/3] libcamera: media_device: Add DeviceInfo features

[Jacopo Mondi]

Hi Laurent,
   thanks for re-submitting these patches

On Wed, Jan 02, 2019 at 02:49:01AM +0200, Laurent Pinchart wrote:
> From: Jacopo Mondi <jacopo at jmondi.org>
>
> Add the features of the DeviceInfo class needed to replace it with
> MediaDevice.
>
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/libcamera/include/media_device.h |  5 +++
>  src/libcamera/media_device.cpp       | 52 ++++++++++++++++++++++++++--
>  2 files changed, 55 insertions(+), 2 deletions(-)
>
> diff --git a/src/libcamera/include/media_device.h b/src/libcamera/include/media_device.h
> index d787be391882..3fcdb4b4d5f8 100644
> --- a/src/libcamera/include/media_device.h
> +++ b/src/libcamera/include/media_device.h
> @@ -24,6 +24,10 @@ public:
>  	MediaDevice(const std::string &devnode);
>  	~MediaDevice();
>
> +	bool acquire();
> +	void release() { acquired_ = false; }
> +	bool busy() const { return acquired_; }
> +
>  	int open();
>  	void close();
>
> @@ -41,6 +45,7 @@ private:
>  	std::string devnode_;
>  	int fd_;
>  	bool valid_;
> +	bool acquired_;
>
>  	std::map<unsigned int, MediaObject *> objects_;
>  	MediaObject *object(unsigned int id);
> diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
> index 1bd4f43a0c79..605e504be124 100644
> --- a/src/libcamera/media_device.cpp
> +++ b/src/libcamera/media_device.cpp
> @@ -52,7 +52,11 @@ namespace libcamera {
>   * controller device node. It can be closed at any time with a call to close().
>   * This will not invalidate the media graph and all cached media objects remain
>   * valid and can be accessed normally. The device can then be later reopened if
> - * needed to perform other operations that interact with the device node.
> + * needed to perform other operations that interect with the device node.

s/interect/interact/

> + *
> + * Media device can be claimed for exclusive use with acquire(), released with
> + * release() and tested with busy(). This mechanism is aimed at pipeline
> + * managers to claim media devices they support during enumeration.
>   */
>
>  /**
> @@ -63,7 +67,7 @@ namespace libcamera {
>   * populated with open() and populate() before the media graph can be queried.
>   */
>  MediaDevice::MediaDevice(const std::string &devnode)
> -	: devnode_(devnode), fd_(-1), valid_(false)
> +	: devnode_(devnode), fd_(-1), valid_(false), acquired_(false)
>  {
>  }
>
> @@ -74,6 +78,50 @@ MediaDevice::~MediaDevice()
>  	clear();
>  }
>
> +/**
> + * \brief Claim a device for exclusive use
> + *
> + * The device claiming mechanism offers simple media device access arbitration
> + * between multiple users. When the media device is created, it is available to
> + * all users. Users can query the media graph to determine whether they can
> + * support the device and, if they do, claim the device for exclusive use. Other
> + * users are then expected to skip over media devices in use as reported by the
> + * busy() function.
> + *
> + * Once claimed the device shall be released by its user when not needed anymore
> + * by calling the release() function.
> + *
> + * Exclusive access is only guaranteed if all users of the media device abide by

s/by/to ?

> + * the device claiming mechanism, as it isn't enforced by the media device
> + * itself.
> + *
> + * \return true if the device was successfully claimed, or false if it was
> + * already in use
> + * \sa release(), busy()
> + */
> +bool MediaDevice::acquire()
> +{
> +	if (acquired_)
> +		return false;
> +
> +	acquired_ = true;
> +	return true;
> +}
> +
> +/**
> + * \fn MediaDevice::release()
> + * \brief Release a device previously claimed for exclusive use
> + * \sa acquire(), busy()
> + */
> +
> +/**
> + * \fn MediaDevice::busy()
> + * \brief Check if a device is in use
> + * \return true if the device has been claimed for exclusive user, or false if

s/user/use

> + * it is available
> + * \sa acquire(), release()
> + */
> +

With this minor things addressed, please push

Thanks
   j


>  /**
>   * \brief Open a media device and retrieve device information
>   *
> --
> Regards,
>
> Laurent Pinchart
>
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> libcamera-devel at lists.libcamera.org
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