Re: [v4l-utils] [PATCH v1 3/3] utils: media-ctl: Support accessing the subdev TRY state

[Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>]

On 10/06/2024 12:00, Laurent Pinchart wrote:
> Hi Tomi,
>
> On Mon, Jun 10, 2024 at 09:14:59AM +0300, Tomi Valkeinen wrote:
> > On 10/06/2024 04:22, Laurent Pinchart wrote:
> > > Add a -W/--which argument to media-ctl to select which state to operate
> > > on. Default to the ACTIVE state to preserve the current behaviour.
> > >
> > > Despite the fact that all values set on the TRY state are lost when
> > > media-ctl terminates, support for the TRY state is useful in order to
> > > retrieve the default configuration of subdevs, or to try configurations.
> >
> > I think this is fine, but I'm curious why you chose such an argument. I
> > would have thought "-t/--try" (or even just --try) would have been
> > simpler to implement and to use. I think I would remember "--try"
> > easily, but "-W TRY", I fear I'll have to check the man page every time...
>
> There are a few reasons:
>
> - Be closer to the API (media-ctl is a low-level tool)
> - Support other values later if the kernel API evolves (no plan for
>    that, but who knows ?)
> - I find it easier to propagate arguments in scripts this way. If a
>    script that wraps media-ctl receives a nothing/--try argument, it's
>    fairly easy to translate that to nothing/-W TRY. If it receives a
>    --foo ACTIVE/TRY argument (on the command line, in an interactive
>    prompt, as part of a string that tells what to do on a pad, ...), then
>    translating that to '-W arg' is easier than to nothing/-W TRY.

Thanks.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>

 Tomi

> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > ---
> > >    utils/media-ctl/media-ctl.c | 13 +++++++------
> > >    utils/media-ctl/options.c   | 18 +++++++++++++++++-
> > >    utils/media-ctl/options.h   |  1 +
> > >    3 files changed, 25 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/utils/media-ctl/media-ctl.c b/utils/media-ctl/media-ctl.c
> > > index 42b1bd9aaa6e..33df0880fd9b 100644
> > > --- a/utils/media-ctl/media-ctl.c
> > > +++ b/utils/media-ctl/media-ctl.c
> > > @@ -600,7 +600,6 @@ static void media_print_topology_text(struct media_device *media,
> > >    
> > >    int main(int argc, char **argv)
> > >    {
> > > -	const enum v4l2_subdev_format_whence which = V4L2_SUBDEV_FORMAT_ACTIVE;
> > >    	struct media_device *media;
> > >    	struct media_entity *entity = NULL;
> > >    	int ret = -1;
> > > @@ -667,7 +666,8 @@ int main(int argc, char **argv)
> > >    			goto out;
> > >    		}
> > >    
> > > -		v4l2_subdev_print_format(pad->entity, pad->index, stream, which);
> > > +		v4l2_subdev_print_format(pad->entity, pad->index, stream,
> > > +					 media_opts.which);
> > >    	}
> > >    
> > >    	if (media_opts.get_dv_pad) {
> > > @@ -709,9 +709,10 @@ int main(int argc, char **argv)
> > >    		media_print_topology_dot(media);
> > >    	} else if (media_opts.print) {
> > >    		if (entity)
> > > -			media_print_topology_text_entity(media, entity, which);
> > > +			media_print_topology_text_entity(media, entity,
> > > +							 media_opts.which);
> > >    		else
> > > -			media_print_topology_text(media, which);
> > > +			media_print_topology_text(media, media_opts.which);
> > >    	} else if (entity) {
> > >    		const char *devname;
> > >    
> > > @@ -741,7 +742,7 @@ int main(int argc, char **argv)
> > >    	}
> > >    
> > >    	if (media_opts.routes) {
> > > -		ret = v4l2_subdev_parse_setup_routes(media, which,
> > > +		ret = v4l2_subdev_parse_setup_routes(media, media_opts.which,
> > >    						     media_opts.routes);
> > >    		if (ret) {
> > >    			printf("Unable to setup routes: %s (%d)\n",
> > > @@ -751,7 +752,7 @@ int main(int argc, char **argv)
> > >    	}
> > >    
> > >    	if (media_opts.formats) {
> > > -		ret = v4l2_subdev_parse_setup_formats(media, which,
> > > +		ret = v4l2_subdev_parse_setup_formats(media, media_opts.which,
> > >    						      media_opts.formats);
> > >    		if (ret) {
> > >    			printf("Unable to setup formats: %s (%d)\n",
> > > diff --git a/utils/media-ctl/options.c b/utils/media-ctl/options.c
> > > index 3c408a1b9b06..3606525c33da 100644
> > > --- a/utils/media-ctl/options.c
> > > +++ b/utils/media-ctl/options.c
> > > @@ -40,6 +40,7 @@
> > >    
> > >    struct media_options media_opts = {
> > >    	.devname = MEDIA_DEVNAME_DEFAULT,
> > > +	.which = V4L2_SUBDEV_FORMAT_ACTIVE,
> > >    };
> > >    
> > >    static void print_version()
> > > @@ -75,6 +76,7 @@ static void usage(const char *argv0)
> > >    	printf("-r, --reset		Reset all links to inactive\n");
> > >    	printf("-v, --verbose		Be verbose\n");
> > >    	printf("    --version		Show version information\n");
> > > +	printf("-W, --which which	Select the subdev state to operate on\n");
> > >    	printf("\n");
> > >    	printf("Links and formats are defined as\n");
> > >    	printf("\tlinks           = link { ',' link } ;\n");
> > > @@ -140,6 +142,8 @@ static void usage(const char *argv0)
> > >    	for (i = V4L2_YCBCR_ENC_DEFAULT; i <= V4L2_YCBCR_ENC_SMPTE240M; i++)
> > >    		printf("\t                %s\n",
> > >    		       v4l2_subdev_ycbcr_encoding_to_string(i));
> > > +
> > > +	printf("\twhich           Subdev state ('ACTIVE' or 'TRY')\n");
> > >    }
> > >    
> > >    #define OPT_PRINT_DOT			256
> > > @@ -168,6 +172,7 @@ static struct option opts[] = {
> > >    	{"reset", 0, 0, 'r'},
> > >    	{"verbose", 0, 0, 'v'},
> > >    	{"version", 0, 0, OPT_VERSION},
> > > +	{"which", 1, 0, 'W'},
> > >    	{ },
> > >    };
> > >    
> > > @@ -244,7 +249,7 @@ int parse_cmdline(int argc, char **argv)
> > >    	}
> > >    
> > >    	/* parse options */
> > > -	while ((opt = getopt_long(argc, argv, "d:e:f:hil:prvV:R:",
> > > +	while ((opt = getopt_long(argc, argv, "d:e:f:hil:prvV:R:W:",
> > >    				  opts, NULL)) != -1) {
> > >    		switch (opt) {
> > >    		case 'd':
> > > @@ -294,6 +299,17 @@ int parse_cmdline(int argc, char **argv)
> > >    			media_opts.routes = optarg;
> > >    			break;
> > >    
> > > +		case 'W':
> > > +			if (!strcmp(optarg, "ACTIVE"))
> > > +				media_opts.which = V4L2_SUBDEV_FORMAT_ACTIVE;
> > > +			else if (!strcmp(optarg, "TRY"))
> > > +				media_opts.which = V4L2_SUBDEV_FORMAT_TRY;
> > > +			else {
> > > +				printf("Invalid 'which' value '%s'\n", optarg);
> > > +				return 1;
> > > +			}
> > > +			break;
> > > +
> > >    		case OPT_PRINT_DOT:
> > >    			media_opts.print_dot = 1;
> > >    			break;
> > > diff --git a/utils/media-ctl/options.h b/utils/media-ctl/options.h
> > > index 753d09347585..095729b98014 100644
> > > --- a/utils/media-ctl/options.h
> > > +++ b/utils/media-ctl/options.h
> > > @@ -37,6 +37,7 @@ struct media_options
> > >    	const char *get_dv_pad;
> > >    	const char *dv_pad;
> > >    	const char *routes;
> > > +	enum v4l2_subdev_format_whence which;
> > >    };
> > >    
> > >    extern struct media_options media_opts;