Hi Niklas,
On Wednesday, 14 February 2018 01:12:50 EET Niklas Söderlund wrote:
> On 2018-02-14 00:31:21 +0200, Laurent Pinchart wrote:
> > On Tuesday, 13 February 2018 18:47:04 EET Niklas Söderlund wrote:
> >> On 2018-02-13 18:26:34 +0200, Laurent Pinchart wrote:
> >>> On Monday, 29 January 2018 18:34:15 EET Niklas Söderlund wrote:
> >>>> There was never proper support in the VIN driver to deliver
> >>>> ALTERNATING field format to user-space, remove this field option. The
> >>>> problem is that ALTERNATING filed order requires the sequence numbers
> >>>> of buffers returned to userspace to reflect if fields where dropped or
> >>>> not, something which is not possible with the VIN drivers capture
> >>>> logic.
> >>>>
> >>>> The VIN driver can still capture from a video source which delivers
> >>>> frames in ALTERNATING field order, but needs to combine them using
> >>>> the VIN hardware into INTERLACED field order. Before this change if a
> >>>> source was delivering fields using ALTERNATE the driver would default
> >>>> to combining them using this hardware feature. Only if the user
> >>>> explicitly requested ALTERNATE filed order would incorrect frames be
> >>>> delivered.
> >>>>
> >>>> The height should not be cut in half for the format for TOP or BOTTOM
> >>>> fields settings. This was a mistake and it was made visible by the
> >>>> scaling refactoring. Correct behavior is that the user should request
> >>>> a frame size that fits the half height frame reflected in the field
> >>>> setting. If not the VIN will do its best to scale the top or bottom
> >>>> to the requested format and cropping and scaling do not work as
> >>>> expected.
> >>>>
> >>>> Signed-off-by: Niklas Söderlund
> >>>> <niklas.soderlund+renesas@xxxxxxxxxxxx>
> >>>> Reviewed-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> >>>> ---
> >>>>
> >>>> drivers/media/platform/rcar-vin/rcar-dma.c | 15 +-------
> >>>> drivers/media/platform/rcar-vin/rcar-v4l2.c | 53
> >>>> +++++++++++------------
> >>>> 2 files changed, 24 insertions(+), 44 deletions(-)
> >
> > [snip]
> >
> >>>> diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> >>>> b/drivers/media/platform/rcar-vin/rcar-v4l2.c index
> >>>> 4d5be2d0c79c9c9a..9f7902d29c62e205 100644
> >>>> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> >>>> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> >>>> @@ -103,6 +103,28 @@ static int rvin_get_source_format(struct
> >>>> rvin_dev *vin,
> >>>> if (ret)
> >>>> return ret;
> >>>>
> >>>> + switch (fmt.format.field) {
> >>>> + case V4L2_FIELD_TOP:
> >>>> + case V4L2_FIELD_BOTTOM:
> >>>> + case V4L2_FIELD_NONE:
> >>>> + case V4L2_FIELD_INTERLACED_TB:
> >>>> + case V4L2_FIELD_INTERLACED_BT:
> >>>> + case V4L2_FIELD_INTERLACED:
> >>>> + break;
> >>>> + case V4L2_FIELD_ALTERNATE:
> >>>> + /*
> >>>> + * Driver do not (yet) support outputting ALTERNATE to a
> >>>> + * userspace. It dose support outputting INTERLACED so use
> >>>
> >>> s/dose/does/
> >>>
> >>>> + * the VIN hardware to combine the two fields.
> >>>> + */
> >>>> + fmt.format.field = V4L2_FIELD_INTERLACED;
> >>>> + fmt.format.height *= 2;
> >>>> + break;
> >>>
> >>> I don't like this much. The rvin_get_source_format() function is
> >>> supposed to return the media bus format for the bus between the source
> >>> and the VIN. It's the caller that should take the field limitations into
> >>> account, otherwise you end up with a mix of source and VIN data in the
> >>> same structure.
> >>
> >> When I read your comments I understand your argument better. And I
> >> understand this function is perhaps poorly named. Maybe it should be
> >> renamed to rvin_get_vin_format_from_source().
> >
> > If you add a comment above the function I could live with that. Would it
> > make sense to pass a v4l2_pix_format structure instead of a
> > v4l2_mbus_framefmt ?
>
> I now see that the function name is misleading and I will change it as
> per above. I will also add a comment and swap to v4l2_pix_format (which
> was used before v10 but was changed due to your review comments, I'm
> happy you come around :-)
The argument type has to be consistent with the function's purpose and name.
Now that you propose changing the function's purpose, my previous comments
have to be updated. And I'm annoyed that you have such a good memory, it
forces me to invent excuses :-)
> >> The source format is fetched at s_stream() time in order to do format
> >> validation. At this time the field is also taken into account once more
> >> to validate that the VIN format (calculated here) still is valid. It
> >> also handles the question you ask later at s_stream() time, see bellow.
> >>
> >>>> + default:
> >>>> + vin->format.field = V4L2_FIELD_NONE;
> >>>> + break;
> >>>> + }
> >>>> +
> >>>> memcpy(mbus_fmt, &fmt.format, sizeof(*mbus_fmt));
> >>>>
> >>>> return 0;
[snip]
--
Regards,
Laurent Pinchart
