Hi, Hans, On Fri, 2017-06-16 at 12:42 +0200, Hans Verkuil wrote: > On 05/12/17 04:42, Minghsiu Tsai wrote: > > From: Daniel Kurtz <djkurtz@xxxxxxxxxxxx> > > > > Experiments show that the: > > (1) mtk-mdp uses the _MPLANE form of CAPTURE/OUTPUT > > Please drop this, since this no longer applies to this patch. > I will remove it next version > > (2) CAPTURE types use CROP targets, and OUTPUT types use COMPOSE targets > > Are you really certain about this? > > For m2m devices the output (i.e. memory to hardware) typically crops from memory > and the capture side (hardware to memory) composes into memory. > > I.e.: for the output side you crop the part of the memory buffer that you want > to process and on the capture side you compose the result into a memory buffer: > i.e. the memory buffer might be 1920x1080, but you compose the decoder output > into a rectangle of 640x480 at offset 128x128 within that buffer (just an example). > > CAPTURE using crop would be if, before the data is DMAed, the hardware decoder > output is cropped. E.g. if the stream fed to the decoder is 1920x1080, but you > want to only DMA a subselection of that, then that would be cropping, and it > would go to a memory buffer of the size of the crop selection. > > OUTPUT using compose is highly unlikely: that means that the frame you give > is composed in a larger internal buffer with generated border data around it. > Very rare and really only something that a compositor of some sort would do. > That's strange. In v4l2-ioctl.c, v4l_g_crop() OUTPUT is using COMPOSE CAPTURE is using CROP static int v4l_g_crop(const struct v4l2_ioctl_ops *ops, struct file *file, void *fh, void *arg) ... /* crop means compose for output devices */ if (V4L2_TYPE_IS_OUTPUT(p->type)) s.target = V4L2_SEL_TGT_COMPOSE_ACTIVE; else s.target = V4L2_SEL_TGT_CROP_ACTIVE; ret = ops->vidioc_g_selection(file, fh, &s); > What exactly does the hardware do? Both for the encoder and for the decoder > case. Perhaps if I knew exactly what that is, then I can advise. > NV12M/YUV420M/MT21 -> MDP -> NV12M/YUV420M The usage would be like this: For decoder: decoder -> MT21 -> MDP -> NV12M/YUV420M For encoder: NV12M/YUV420M -> MDP -> NV12M/YUV420M -> encoder > Regards, > > Hans > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
