[libcamera-devel] [PATCH 2/2] libcamera: Switch internal YAML files to YAML 1.1

[Laurent Pinchart]

On Thu, Aug 04, 2022 at 03:59:36PM +0100, Kieran Bingham wrote:
> Quoting Laurent Pinchart via libcamera-devel (2022-08-04 14:21:12)
> > The python3-yaml package shipped by Debian is based on libyaml 0.2.2,
> > which doesn't support YAML 1.2. It is documented as such:
> > 
> >     Python3-yaml is a complete YAML 1.1 parser and emitter for Python3.
> > 
> > For some reasons the internal YAML files used to generate format- and
> > control-related source files still parse correctly, despite the YAML 1.2
> > directive at the beginning. Still, given that we don't use any feature
> > of YAML 1.2, and that the tuning data files now use YAML 1.1, switch the
> > internal YAML files to version 1.1 as well for consistency.
> > 
> > The main drawback of YAML 1.1 is that the unquoted literal strings Yes,
> > No, On and Off will be parsed as booleans. We need to be careful to
> > avoid those values in YAML files, until libcamera can switch to YAML 1.2
> > once more recent versions of libyaml get shipped by the distributions we
> > want to support.
> 
> I wonder if this also potentially explains why I saw quite a lot of odd
> pixel format issues the other day.

I'd be surprised, as this is related to build time, not run time.

I've looked at the pyyaml implementation, and it only checks that the
major version is 1, it ignores the minor version. I'll update the commit
message to

libcamera: Switch internal YAML files to YAML 1.1

The python3-yaml package (containing the PyYAML Python package) shipped
by Debian stable is documented as a YAML 1.1 parser:

    Python3-yaml is a complete YAML 1.1 parser and emitter for Python3.

PyYAML doesn't implement YAML 1.2 support, but ignores the minor number
of the YAML directive, and thus doesn't choke on the libcamera internal
files used to generate format- and control-related source code that
explicitly state conformance with YAML 1.2. Still, given that we don't
use any feature of YAML 1.2, and that the tuning data files now use YAML
1.1, switch the internal YAML files to version 1.1 as well for
consistency.

The main drawback of YAML 1.1 is that the unquoted literal strings Yes,
No, On and Off will be parsed as booleans. We need to be careful to
avoid those values in YAML files, until libcamera can switch to YAML 1.2
once more recent versions of libyaml get shipped by the distributions we
want to support. This is however not an issue introduced by this change,
as the existing YAML 1.2 files were parsed with the YAML 1.1 string
literal parsing rules anyway.

> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  src/libcamera/control_ids.yaml  | 2 +-
> >  src/libcamera/formats.yaml      | 2 +-
> >  src/libcamera/property_ids.yaml | 2 +-
> >  3 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
> > index ecab3ae97260..5510feefdfeb 100644
> > --- a/src/libcamera/control_ids.yaml
> > +++ b/src/libcamera/control_ids.yaml
> > @@ -2,7 +2,7 @@
> >  #
> >  # Copyright (C) 2019, Google Inc.
> >  #
> > -%YAML 1.2
> > +%YAML 1.1
> >  ---
> >  # Unless otherwise stated, all controls are bi-directional, i.e. they can be
> >  # set through Request::controls() and returned out through Request::metadata().
> > diff --git a/src/libcamera/formats.yaml b/src/libcamera/formats.yaml
> > index d3fbf5f47211..e586cde1d705 100644
> > --- a/src/libcamera/formats.yaml
> > +++ b/src/libcamera/formats.yaml
> > @@ -2,7 +2,7 @@
> >  #
> >  # Copyright (C) 2020, Google Inc.
> >  #
> > -%YAML 1.2
> > +%YAML 1.1
> >  ---
> >  formats:
> >    - R8:
> > diff --git a/src/libcamera/property_ids.yaml b/src/libcamera/property_ids.yaml
> > index 11b7ebdc3105..cb55e0ed2283 100644
> > --- a/src/libcamera/property_ids.yaml
> > +++ b/src/libcamera/property_ids.yaml
> > @@ -2,7 +2,7 @@
> >  #
> >  # Copyright (C) 2019, Google Inc.
> >  #
> > -%YAML 1.2
> > +%YAML 1.1
> >  ---
> >  controls:
> >    - Location:

-- 
Regards,

Laurent Pinchart