Re: [PATCH v4 33/36] media: imx: redo pixel format enumeration and negotiation

[Steve Longerbeam]

On 02/23/2017 01:10 AM, Philipp Zabel wrote:
> Hi Steve,
>
> On Wed, 2017-02-22 at 15:52 -0800, Steve Longerbeam wrote:
> > Hi Philipp,
> >
> >
> > On 02/16/2017 03:32 AM, Philipp Zabel wrote:
> > > On Wed, 2017-02-15 at 18:19 -0800, Steve Longerbeam wrote:
> > > > The previous API and negotiation of mbus codes and pixel formats
> > > > was broken, and has been completely redone.
> > > >
> > > > The negotiation of media bus codes should be as follows:
> > > >
> > > > CSI:
> > > >
> > > > sink pad     direct src pad      IDMAC src pad
> > > > --------     ----------------    -------------
> > > > RGB (any)        IPU RGB           RGB (any)
> > > > YUV (any)        IPU YUV           YUV (any)
> > > > Bayer              N/A             must be same bayer code as sink
> > >
> > > The IDMAC src pad should also use the internal 32-bit RGB / YUV format,
> > > except if bayer/raw mode is selected, in which case the attached capture
> > > video device should only allow a single mode corresponding to the output
> > > pad media bus format.
> >
> > The IDMAC source pad is going to memory, so it has left the IPU.
> > Are you sure it should be an internal IPU format? I realize it
> > is linked to a capture device node, and the IPU format could then
> > be translated to a v4l2 fourcc by the capture device, but IMHO this
> > pad is external to the IPU.
>
> The CSI IDMAC source pad should describe the format at the connection
> between the CSI and the IDMAC, just as the icprpvf and icprpenc source
> pads.
> The format outside of the IPU is the memory format written by the IDMAC,
> but that is a memory pixel format and not a media bus format at all.

True, it is a memory format. I don't really mind if the CSI and PRP
ENC/VF source pads are characterized as IPU internal formats, since
they are only used to indicate the colorspace to the capture device.

And yes it did simplify the enumeration and try_fmt code a bit. So
I went ahead and made the change.

Steve


> That would also make it more straightforward to enumerate the memory
> pixel formats in the capture device: If the source pad media bus format
> is 32-bit YUV, enumerate all YUV formats, if it is 32-bit RGB or RGB565,
> enumerate all rgb formats, otherwise (bayer/raw mode) only allow the
> specific memory format matching the bus format.