Re: [PATCH v6 02/13] media: v4l2-fwnode: add v4l2_fwnode_connector

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Marco,

On Thu, Aug 15, 2019 at 03:04:37PM +0200, Marco Felsch wrote:
> On 19-08-15 15:38, Laurent Pinchart wrote:
> > On Fri, Aug 09, 2019 at 09:55:36AM +0200, Marco Felsch wrote:
> >> On 19-05-16 19:36, Laurent Pinchart wrote:
> >>> On Mon, Apr 15, 2019 at 02:44:02PM +0200, Marco Felsch wrote:
> >>>> Currently every driver needs to parse the connector endpoints by it self.
> >>> 
> >>> s/it self/itself/
> >>> 
> >>>> This is the initial work to make this generic. The generic connector has
> >>>> some common fields and some connector specific parts. The generic one
> >>>> includes:
> >>>>   - type
> >>>>   - label
> >>>>   - remote_port (the port where the connector is connected to)
> >>>>   - remote_id   (the endpoint where the connector is connected to)
> >>> 
> >>> This assumes a single connection between a connector and a remote port,
> >>> and a single port on the connector side. Is this guaranteed ? For the
> >>> mini-DIN-4 connectors (often used for S-Video) for instance, I recall
> >>> from the extensive discussions we had in the past that they should be
> >>> modeled with two pins, one for the Y component and one for C components.
> >>> The rationale for this is to support systems where such a connector
> >>> could be used to carry S-Video, but also two composite video signals
> >>> (usually through an external adapter from 2 RCA female connectors to one
> >>> S-Video male connector) that would be routed to two separate video
> >>> decoders (or two different inputs of the same video decoder). Other
> >>> topologies may be possible too.
> >> 
> >> I got your concerns and I also remember the tvp5150 port bindings
> >> myself in the past. Do you know how often such a setup you described
> >> above happens these days? I would rather add more documentation to the
> >> bindings [1] and add a check to v4l2_fwnode_parse_connector() to
> >> guarantee that one port has only one endpoint. Because I don't think
> >> that analog connectors has a bright future these days.
> >> 
> >> [1] Documentation/devicetree/bindings/display/connector/ \
> >>     analog-tv-connector.txt
> > 
> > I have seen it on older hardware, I don't know about more recent
> > systems. For the S-Video case at least, you need to support two DT
> > ports, even if you don't support connecting them to two different
> > devices yet.
> 
> Can you take a look on the v7 I send a few minutes ago? I changed the
> layout ;)

I'll try to get to that ASAP, but I have a Rockchip driver to review
first :-)

> > In any case, I'm fine if those topologies are not supported yet, but it
> > should be possible to support them in a backward-compatible way. In
> > particular, in this case, we should make sure the DT bindings will allow
> > such topologies, and the DT parsing API should make it possible to
> > support them without fugure changes to drivers that use the API from
> > this patch for "simple" topologies.
> 
> You're right. I adapted the struct to be more extendible.
> 
> >>>> The specific fields are within a union, since only one of them can be
> >>>> available at the time. Since this is the initial support the patch adds
> >>>> only the analog-connector specific ones.
> >>>> 
> >>>> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> >>>> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
> >>>> ---
> >>>> [1] https://patchwork.kernel.org/cover/10794703/
> >>>> 
> >>>> v6:
> >>>> - fix some spelling and style issues
> >>>> - rm unnecessary comments
> >>>> - drop vga and dvi connector
> >>>> 
> >>>> v2-v4:
> >>>> - nothing since the patch was squashed from series [1] into this
> >>>>   series.
> >>>> 
> >>>>  include/media/v4l2-connector.h | 30 ++++++++++++++++++++++++++++++
> >>>>  include/media/v4l2-fwnode.h    | 33 +++++++++++++++++++++++++++++++++
> >>>>  2 files changed, 63 insertions(+)
> >>>>  create mode 100644 include/media/v4l2-connector.h
> >>>> 
> >>>> diff --git a/include/media/v4l2-connector.h b/include/media/v4l2-connector.h
> >>>> new file mode 100644
> >>>> index 000000000000..3a951c54f50e
> >>>> --- /dev/null
> >>>> +++ b/include/media/v4l2-connector.h
> >>>> @@ -0,0 +1,30 @@
> >>>> +/* SPDX-License-Identifier: GPL-2.0-only */
> >>>> +/*
> >>>> + * v4l2-connector.h
> >>>> + *
> >>>> + * V4L2 connector types.
> >>>> + *
> >>>> + * Copyright 2019 Pengutronix, Marco Felsch <kernel@pengutronix.de>
> >>>> + */
> >>>> +
> >>>> +#ifndef V4L2_CONNECTOR_H
> >>>> +#define V4L2_CONNECTOR_H
> >>>> +
> >>>> +#define V4L2_CONNECTOR_MAX_LABEL 41
> >>> 
> >>> Hans pointed out this was a weird number. Should you turn the label
> >>> field into a pointer to make this more generic (with a
> >>> v4l2_fwnode_connector_cleanup() function then) ?
> >> 
> >> Yes, that would be the better approach. I will change that.
> >> 
> >>>> +
> >>>> +/**
> >>>> + * enum v4l2_connector_type - connector type
> >>>> + * @V4L2_CON_UNKNOWN:   unknown connector type, no V4L2 connetor configuration
> >>>> + * @V4L2_CON_COMPOSITE: analog composite connector
> >>>> + * @V4L2_CON_SVIDEO:    analog svideo connector
> >>>> + * @V4L2_CON_HDMI:      digital hdmi connector
> >>>> + */
> >>>> +enum v4l2_connector_type {
> >>>> +	V4L2_CON_UNKNOWN,
> >>>> +	V4L2_CON_COMPOSITE,
> >>>> +	V4L2_CON_SVIDEO,
> >>>> +	V4L2_CON_HDMI,
> >>>> +};
> >>>> +
> >>>> +#endif /* V4L2_CONNECTOR_H */
> >>>> +
> >>>> diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
> >>>> index 6c07825e18b9..f4df1b95c5ef 100644
> >>>> --- a/include/media/v4l2-fwnode.h
> >>>> +++ b/include/media/v4l2-fwnode.h
> >>>> @@ -22,6 +22,7 @@
> >>>>  #include <linux/list.h>
> >>>>  #include <linux/types.h>
> >>>>  
> >>>> +#include <media/v4l2-connector.h>
> >>>>  #include <media/v4l2-mediabus.h>
> >>>>  #include <media/v4l2-subdev.h>
> >>>>  
> >>>> @@ -126,6 +127,38 @@ struct v4l2_fwnode_link {
> >>>>  	unsigned int remote_port;
> >>>>  };
> >>>>  
> >>>> +/**
> >>>> + * struct v4l2_fwnode_connector_analog - analog connector data structure
> >>>> + * @supported_tvnorms: tv norms this connector supports, set to V4L2_STD_ALL
> >>>> + *                     if no restrictions are specified.
> >>>> + */
> >>>> +struct v4l2_fwnode_connector_analog {
> >>>> +	v4l2_std_id supported_tvnorms;
> >>>> +};
> >>>> +
> >>>> +/**
> >>>> + * struct v4l2_fwnode_connector - the connector data structure
> >>>> + * @remote_port: identifier of the remote endpoint port the connector connects
> >>>> + *		 to
> >>>> + * @remote_id: identifier of the remote endpoint the connector connects to
> >>>> + * @label: connetor label
> >>>> + * @type: connector type
> >>>> + * @connector: connector configuration
> >>>> + * @connector.analog: analog connector configuration
> >>>> + *                    &struct v4l2_fwnode_connector_analog
> >>>> + */
> >>>> +struct v4l2_fwnode_connector {
> >>>> +	unsigned int remote_port;
> >>>> +	unsigned int remote_id;
> >>>> +	char label[V4L2_CONNECTOR_MAX_LABEL];
> >>>> +	enum v4l2_connector_type type;
> >>>> +
> >>>> +	union {
> >>>> +		struct v4l2_fwnode_connector_analog analog;
> >>>> +		/* future connectors */
> >>>> +	} connector;
> >>>> +};
> >>>> +
> >>>>  /**
> >>>>   * v4l2_fwnode_endpoint_parse() - parse all fwnode node properties
> >>>>   * @fwnode: pointer to the endpoint's fwnode handle

-- 
Regards,

Laurent Pinchart