Hi Niklas,

On Sat, Aug 1, 2020 at 11:18 AM Niklas [off-list ref] wrote:

On 2020-07-25 23:23:13 +0100, Lad, Prabhakar wrote:

quoted

On Sat, Jul 25, 2020 at 9:11 AM Niklas [off-list ref] wrote:

quoted

On 2020-07-24 22:11:31 +0100, Lad, Prabhakar wrote:

quoted

On Fri, Jul 24, 2020 at 8:37 PM Niklas [off-list ref] wrote:

quoted

On 2020-07-24 15:58:51 +0100, Lad Prabhakar wrote:

quoted

Add a DT property "renesas-vin-ycbcr-8b-g" to select YCbCr422 8-bit data
input pins.

quoted

quoted

quoted

quoted

This nit apart I'm not sure a property is the right way here. Could it
not be possible on some designs to have two different sensors one wired
to DATA[7:0] and the other to DATA[15:8] and by controlling the
VNDRM2_YDS register at runtime switch between the two? If so adding a DT
property to hard-code one of the two options would prevent this. I fear
we need to think of a runtime way to deal with this.

Aha Gen2 and Gen3 hardware manuals have a bit different description
about the YDS field. (I was working R8a7742 SoC so I referred Gen2
manual)

Ahh, I think we should use the Gen3 names as I find them overall an
improvement over the Gen2 ones.

Agreed.

quoted

quoted

quoted

The best way to do that I think is to extend the port@0 node to allow
for two endpoints, one for each of the two possible parallel sensors.
This would then have to be expressed in the media graph and selection if
YDS should be set or not depend on which media links are enabled.

In that case how do we handle endpoint matching each would have two
subdevs to be matched.

It would be handle in the same was as the multiple endpoints in port@1.

quoted

And in case non media-ctl cases we cannot
switch between subdevs.

For the Gen2 none media graph enabled mode this could be handled with
the S_INPUT ioctl. For this feature to be merged however I it needs to
be possible to select input both in Gen2 and Gen3 I'm afraid.

Ohh yes S_INPUT could be used to switch inputs. But  how do we decide
YDS needs to be enabled, for example with the below dts say vin3 is
parallel bus split into 2x 8-bit bus one connected to a ov5640 sensor
and other connected to ov7725 sensor. Should we use data-shift
property for the second vin endpoint (vin3ep1) to enable YDS ?

Using data-shift is a great idea! If I understand your use-case you
currently only have one sensor attached on the parallel bus right? If so
we can postpone the multi sensor part until it's needed and just learn
the VIN driver about data-shift. From the documentation,

  - data-shift: on the parallel data busses, if bus-width is used to
    specify the number of data lines, data-shift can be used to specify
    which data lines are used, e.g. "bus-width=<8>; data-shift=<2>;"
    means, that lines 9:2 are used.

So in this case would not specifying data-shift=<8> solve the DT
description problem? The VIN driver still needs to learn about this tho.

And the PFC drivers need to be extended with the data8_sft8 groups
(present in the BSP), right?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds