[libcamera-devel] [PATCH v2 08/12] android: camera_device: Query plane length

[Laurent Pinchart]

On Mon, Aug 03, 2020 at 07:30:59PM +0300, Laurent Pinchart wrote:
> Hi Kieran,
> 
> Thank you for the patch.
> 
> On Mon, Aug 03, 2020 at 05:18:12PM +0100, Kieran Bingham wrote:
> > Use lseek to query the length of planes where possible rather than leaving
> > the plane.length as zero, which prevents mapping buffers for software
> > processing.
> > 
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> > ---
> > v2:
> >  - no longer support an invalid plane length.
> > ---
> >  src/android/camera_device.cpp | 13 +++++++------
> >  1 file changed, 7 insertions(+), 6 deletions(-)
> > 
> > diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> > index 78b0246e40f0..9f3f3315aed4 100644
> > --- a/src/android/camera_device.cpp
> > +++ b/src/android/camera_device.cpp
> > @@ -1036,12 +1036,13 @@ FrameBuffer *CameraDevice::createFrameBuffer(const buffer_handle_t camera3buffer
> >  			break;
> >  		}
> >  
> > -		/*
> > -		 * Setting length to zero here is OK as the length is only used
> > -		 * to map the memory of the plane. Libcamera do not need to poke
> > -		 * at the memory content queued by the HAL.
> > -		 */
> > -		plane.length = 0;
> > +		off_t length = lseek(plane.fd.fd(), 0, SEEK_END);
> > +		if (length == -1) {
> > +			LOG(HAL, Error) << "Failed to query plane length";
> > +			break;

I spoke too fast. This will cause the function to return a FrameBuffer
with a too small number of planes. You should instead return nullptr
here.

The Rb tag still holds.

> > +		}
> > +
> > +		plane.length = length;
> >  		planes.push_back(std::move(plane));
> >  	}
> >  

-- 
Regards,

Laurent Pinchart