[libcamera-devel] [PATCH v2] libcamera: v4l2device: Obtain device capabilities

[Laurent Pinchart]

On Wed, Jan 23, 2019 at 06:09:09PM +0200, Laurent Pinchart wrote:
> Hi Niklas,

Or maybe Kieran. This clearly shows I should automate name extraction
from the sender :-)

> Thank you for the patch.
> 
> On Wed, Jan 23, 2019 at 01:45:30PM +0000, Kieran Bingham wrote:
> > The capabilities structure from the kernel can return capabilities of the
> > driver, or potentially more specific device capabilities.
> > 
> > Handle this with an inline function 'device_caps()' to return the device
> > specific capabilities when available, or fall back to the driver capabilities
> > otherwise.
> > 
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> >  src/libcamera/include/v4l2_device.h | 12 +++++++++---
> >  src/libcamera/v4l2_device.cpp       |  7 +++++++
> >  2 files changed, 16 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> > index b92e1f1c96c3..cb3601ca070c 100644
> > --- a/src/libcamera/include/v4l2_device.h
> > +++ b/src/libcamera/include/v4l2_device.h
> > @@ -26,10 +26,16 @@ struct V4L2Capability final : v4l2_capability {
> >  	{
> >  		return reinterpret_cast<const char *>(v4l2_capability::bus_info);
> >  	}
> > +	unsigned int device_caps() const
> > +	{
> > +		return capabilities & V4L2_CAP_DEVICE_CAPS
> > +				    ? v4l2_capability::device_caps
> > +				    : v4l2_capability::capabilities;
> > +	}
> >  
> > -	bool isCapture() const { return capabilities & V4L2_CAP_VIDEO_CAPTURE; }
> > -	bool isOutput() const { return capabilities & V4L2_CAP_VIDEO_OUTPUT; }
> > -	bool hasStreaming() const { return capabilities & V4L2_CAP_STREAMING; }
> > +	bool isCapture() const { return device_caps() & V4L2_CAP_VIDEO_CAPTURE; }
> > +	bool isOutput() const { return device_caps() & V4L2_CAP_VIDEO_OUTPUT; }
> > +	bool hasStreaming() const { return device_caps() & V4L2_CAP_STREAMING; }
> 
> We're probably reaching the limit of what inline functions should do. If
> another layer of indirection is needed we may want to de-inline some of
> the functions. It's fine for now.
> 
> >  };
> >  
> >  class MediaEntity;
> > diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> > index 2b17fa1eb0e8..0ce2b187f2f0 100644
> > --- a/src/libcamera/v4l2_device.cpp
> > +++ b/src/libcamera/v4l2_device.cpp
> > @@ -49,6 +49,13 @@ LOG_DEFINE_CATEGORY(V4L2)
> >   * \return The string containing the device location
> >   */
> >  
> > +/**
> > + * \fn unsigned int V4L2Capability::device_caps()
> > + * \brief Retrieve the capabilities of the device
> > + * \return The device specific capabilities if V4L2_CAP_DEVICE_CAPS is set or
> > + * 	   driver capabilities otherwise
> 
> No need for special indentation here. This doesn't require a fix in a
> follow-up patch, but you could fix it if you touch this code later.
> 
> > + */
> > +
> >  /**
> >   * \fn bool V4L2Capability::isCapture()
> >   * \brief Identify if the device is capable of capturing video

-- 
Regards,

Laurent Pinchart