On Thu, 2019-01-24 at 10:24 +0100, Hans Verkuil wrote:
> Resurrecting this thread, since this functionality would be really useful :-)
>
Thanks for the resurrection chant :-)
> On 11/10/18 12:17 PM, Ezequiel Garcia wrote:
> > On Sat, 2018-11-10 at 12:09 +0100, Hans Verkuil wrote:
> > > On 11/10/2018 12:01 PM, Ezequiel Garcia wrote:
> > > > On Sat, 2018-11-10 at 11:29 +0100, Hans Verkuil wrote:
> > > > > On 11/09/2018 10:52 PM, Ezequiel Garcia wrote:
> > > > > > This tool allows to find a device by driver name,
> > > > > > this is useful for scripts to be written in a generic way.
> > > > >
> > > > > Why not add support for this to v4l2-sysfs-path? And improve it at the same
> > > > > time (swradio devices do not show up when I run v4l2-sysfs-path, I also suspect
> > > > > v4l-touch devices aren't recognized. Ditto for media devices.
> > > > >
> > > >
> > > > I can add the functionality to v4l2-sysfs-path, and we can document
> > > > the rest in some TODO list, as I don't think we need to get everything
> > > > solved right now :-)
> > >
> > > I agree with that.
> > >
> >
> > Great!
> >
> > About adding it to v4l2-sysfs-path, is there any scenario where we'll want
> > to use udev-based scanning instead of sysfs-based? Maybe we can rename
> > the tool, and still install a v4l2-sysfs-path alias?
>
> To be honest, I don't know. It appears that sysfs is the most generic approach
> and I have seen cases where udev isn't installed on an embedded system.
>
> So I feel that sysfs is the best approach for now.
>
> BTW, I've added support for swradio and v4l-touch devices to v4l2-sysfs-path, but I
> noticed that it didn't recognize media devices, I need to dig into it a bit to
> understand how to find those devices.
>
OK, I will try to post a new version shortly.
Thanks,
Eze
> Regards,
>
> Hans
>
> > > > > > Usage:
> > > > > >
> > > > > > v4l2-get-device -d uvcvideo -c V4L2_CAP_VIDEO_CAPTURE
> > > > > > /dev/video0
> > > > > > /dev/video2
> > > > > >
> > > > > > Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> > > > > > ---
> > > > > > configure.ac | 1 +
> > > > > > utils/Makefile.am | 1 +
> > > > > > utils/v4l2-get-device/.gitignore | 1 +
> > > > > > utils/v4l2-get-device/Makefile.am | 4 +
> > > > > > utils/v4l2-get-device/v4l2-get-device.c | 147 ++++++++++++++++++++++++
> > > > > > v4l-utils.spec.in | 1 +
> > > > > > 6 files changed, 155 insertions(+)
> > > > > > create mode 100644 utils/v4l2-get-device/.gitignore
> > > > > > create mode 100644 utils/v4l2-get-device/Makefile.am
> > > > > > create mode 100644 utils/v4l2-get-device/v4l2-get-device.c
> > > > > >
> > > > > > diff --git a/configure.ac b/configure.ac
> > > > > > index 5cc34c248fbf..918cb59704b9 100644
> > > > > > --- a/configure.ac
> > > > > > +++ b/configure.ac
> > > > > > @@ -31,6 +31,7 @@ AC_CONFIG_FILES([Makefile
> > > > > > utils/v4l2-compliance/Makefile
> > > > > > utils/v4l2-ctl/Makefile
> > > > > > utils/v4l2-dbg/Makefile
> > > > > > + utils/v4l2-get-device/Makefile
> > > > > > utils/v4l2-sysfs-path/Makefile
> > > > > > utils/qv4l2/Makefile
> > > > > > utils/cec-ctl/Makefile
> > > > > > diff --git a/utils/Makefile.am b/utils/Makefile.am
> > > > > > index 2d5070288c13..2b2b27107d13 100644
> > > > > > --- a/utils/Makefile.am
> > > > > > +++ b/utils/Makefile.am
> > > > > > @@ -9,6 +9,7 @@ SUBDIRS = \
> > > > > > v4l2-compliance \
> > > > > > v4l2-ctl \
> > > > > > v4l2-dbg \
> > > > > > + v4l2-get-device \
> > > > > > v4l2-sysfs-path \
> > > > > > cec-ctl \
> > > > > > cec-compliance \
> > > > > > diff --git a/utils/v4l2-get-device/.gitignore b/utils/v4l2-get-device/.gitignore
> > > > > > new file mode 100644
> > > > > > index 000000000000..b222144c9f4e
> > > > > > --- /dev/null
> > > > > > +++ b/utils/v4l2-get-device/.gitignore
> > > > > > @@ -0,0 +1 @@
> > > > > > +v4l2-get-device
> > > > > > diff --git a/utils/v4l2-get-device/Makefile.am b/utils/v4l2-get-device/Makefile.am
> > > > > > new file mode 100644
> > > > > > index 000000000000..2e5a6e0ba32f
> > > > > > --- /dev/null
> > > > > > +++ b/utils/v4l2-get-device/Makefile.am
> > > > > > @@ -0,0 +1,4 @@
> > > > > > +bin_PROGRAMS = v4l2-get-device
> > > > > > +v4l2_get_device_SOURCES = v4l2-get-device.c
> > > > > > +v4l2_get_device_LDADD = ../libmedia_dev/libmedia_dev.la
> > > > > > +v4l2_get_device_LDFLAGS = $(ARGP_LIBS)
> > > > > > diff --git a/utils/v4l2-get-device/v4l2-get-device.c b/utils/v4l2-get-device/v4l2-get-device.c
> > > > > > new file mode 100644
> > > > > > index 000000000000..f9cc323b7057
> > > > > > --- /dev/null
> > > > > > +++ b/utils/v4l2-get-device/v4l2-get-device.c
> > > > > > @@ -0,0 +1,147 @@
> > > > > > +/*
> > > > > > + * Copyright © 2018 Collabora, Ltd.
> > > > > > + *
> > > > > > + * Based on v4l2-sysfs-path by Mauro Carvalho Chehab:
> > > > > > + *
> > > > > > + * Copyright © 2011 Red Hat, Inc.
> > > > > > + *
> > > > > > + * Permission to use, copy, modify, distribute, and sell this software
> > > > > > + * and its documentation for any purpose is hereby granted without
> > > > > > + * fee, provided that the above copyright notice appear in all copies
> > > > > > + * and that both that copyright notice and this permission notice
> > > > > > + * appear in supporting documentation, and that the name of Red Hat
> > > > > > + * not be used in advertising or publicity pertaining to distribution
> > > > > > + * of the software without specific, written prior permission. Red
> > > > > > + * Hat makes no representations about the suitability of this software
> > > > > > + * for any purpose. It is provided "as is" without express or implied
> > > > > > + * warranty.
> > > > > > + *
> > > > > > + * THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
> > > > > > + * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
> > > > > > + * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
> > > > > > + * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
> > > > > > + * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
> > > > > > + * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
> > > > > > + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
> > > > > > + *
> > > > > > + */
> > > > > > +
> > > > > > +#include <argp.h>
> > > > > > +#include <config.h>
> > > > > > +#include <fcntl.h>
> > > > > > +#include <stdio.h>
> > > > > > +#include <stdlib.h>
> > > > > > +#include <string.h>
> > > > > > +#include <sys/types.h>
> > > > > > +#include <sys/stat.h>
> > > > > > +#include <sys/ioctl.h>
> > > > > > +#include <sys/unistd.h>
> > > > > > +
> > > > > > +#include <linux/videodev2.h>
> > > > > > +
> > > > > > +#include "../libmedia_dev/get_media_devices.h"
> > > > > > +
> > > > > > +const char *argp_program_version = "v4l2-get-device " V4L_UTILS_VERSION;
> > > > > > +const char *argp_program_bug_address = "Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>";
> > > > > > +
> > > > > > +struct args {
> > > > > > + const char *driver;
> > > > > > + unsigned int device_caps;
> > > > > > +};
> > > > > > +
> > > > > > +static const struct argp_option options[] = {
> > > > > > + {"driver", 'd', "DRIVER", 0, "device driver name", 0},
> > > > > > + {"v4l2-device-caps", 'c', "CAPS", 0, "v4l2 device capabilities", 0},
> > > > >
> > > > > I'd like a bus-info option as well, if possible.
> > > > >
> > > >
> > > > Guess that works.
> > > >
> > > > > > + { 0 }
> > > > > > +};
> > > > > > +
> > > > > > +static unsigned int parse_capabilities(const char *arg)
> > > > > > +{
> > > > > > + char *s, *str = strdup(arg);
> > > > > > + unsigned int caps = 0;
> > > > > > +
> > > > > > + s = strtok (str,",");
> > > > > > + while (s != NULL) {
> > > > > > + if (!strcmp(s, "V4L2_CAP_VIDEO_CAPTURE"))
> > > > > > + caps |= V4L2_CAP_VIDEO_CAPTURE;
> > > > > > + else if (!strcmp(s, "V4L2_CAP_VIDEO_OUTPUT"))
> > > > > > + caps |= V4L2_CAP_VIDEO_OUTPUT;
> > > > > > + else if (!strcmp(s, "V4L2_CAP_VIDEO_OVERLAY"))
> > > > > > + caps |= V4L2_CAP_VIDEO_OVERLAY;
> > > > > > + else if (!strcmp(s, "V4L2_CAP_VBI_CAPTURE"))
> > > > > > + caps |= V4L2_CAP_VBI_CAPTURE;
> > > > > > + else if (!strcmp(s, "V4L2_CAP_VBI_OUTPUT"))
> > > > > > + caps |= V4L2_CAP_VBI_OUTPUT;
> > > > >
> > > > > Let's support all CAPS here. I'd also drop the V4L2_CAP_ prefix (or make it optional)
> > > > > and make the strcmp case-insensitive to ease typing.
> > > > >
> > > >
> > > > OK.
> > > >
> > > > > > + s = strtok (NULL, ",");
> > > > > > + }
> > > > > > + free(str);
> > > > > > + return caps;
> > > > > > +}
> > > > > > +
> > > > > > +static error_t parse_opt(int k, char *arg, struct argp_state *state)
> > > > > > +{
> > > > > > + struct args *args = state->input;
> > > > > > +
> > > > > > + switch (k) {
> > > > > > + case 'd':
> > > > > > + args->driver = arg;
> > > > > > + break;
> > > > > > + case 'c':
> > > > > > + args->device_caps = parse_capabilities(arg);
> > > > > > + break;
> > > > > > + default:
> > > > > > + return ARGP_ERR_UNKNOWN;
> > > > > > + }
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > +static struct argp argp = {
> > > > > > + .options = options,
> > > > > > + .parser = parse_opt,
> > > > > > +};
> > > > > > +
> > > > > > +int main(int argc, char *argv[])
> > > > > > +{
> > > > > > + const char *vid;
> > > > > > + struct args args;
> > > > > > + void *md;
> > > > > > +
> > > > > > + args.driver = NULL;
> > > > > > + args.device_caps = 0;
> > > > > > + argp_parse(&argp, argc, argv, 0, 0, &args);
> > > > > > +
> > > > > > + md = discover_media_devices();
> > > > >
> > > > > I never really liked this. My main problem is that it doesn't know about media devices.
> > > > >
> > > >
> > > > Sorry, not sure what you don't really like?
> > > >
> > > > The discover_media_devices() is maybe not the best API, but it's what v4l2-sysfs-path
> > > > uses, and it seemed to fit what we need as a first step (to find v4l2 devices).
> > > >
> > > > Perhaps we can use this for now and pospone improving the discovery library?
> > >
> > > Yes, that can be postponed (I should have been clear about that, sorry).
> > >
> > > > > In my view it should look for media devices first, query them and get all the device
> > > > > nodes referenced in the topology, and then fall back to the old method to discover
> > > > > any remaining device nodes for drivers that do not create a media device.
> > > > >
> > > > > You need media device support anyway since you also want to be able to query the media
> > > > > device for a specific driver and find the device node for a specific entity.
> > > > >
> > > >
> > > > I've been thinking about this (since I started with http://git.ideasonboard.org/media-enum.git),
> > > > but to be honest, I failed to see why I would want to query media devices.
> > > >
> > > > Let's say we want to find a H264 decoder, I don't think the topology is be
> > > > of much use, is it?
> > >
> > > Not for codecs, but this should become a generic utility that you can also use to find
> > > e.g. v4l-subdev device nodes from a complex camera driver.
> > >
> >
> > Ah, that makes sense.
> >
> > Thanks for the quick review!
> >
> > > Regards,
> > >
> > > Hans
> > >
> > > > In any case, I think this is part of a bigger discussion, would you consider merging
> > > > v4l discovery for now?
> > > >
> > > > > > +
> > > > > > + vid = NULL;
> > > > > > + do {
> > > > > > + struct v4l2_capability cap;
> > > > > > + char devnode[64];
> > > > > > + int ret;
> > > > > > + int fd;
> > > > > > +
> > > > > > + vid = get_associated_device(md, vid, MEDIA_V4L_VIDEO,
> > > > > > + NULL, NONE);
> > > > > > + if (!vid)
> > > > > > + break;
> > > > > > + snprintf(devnode, 64, "/dev/%s", vid);
> > > > > > + fd = open(devnode, O_RDWR);
> > > > > > + if (fd < 0)
> > > > > > + continue;
> > > > > > +
> > > > > > + memset(&cap, 0, sizeof cap);
> > > > > > + ret = ioctl(fd, VIDIOC_QUERYCAP, &cap);
> > > > > > + if (ret) {
> > > > > > + close(fd);
> > > > > > + continue;
> > > > > > + }
> > > > > > + close(fd);
> > > > > > +
> > > > > > + if (strncmp(args.driver, (char *)cap.driver, sizeof(cap.driver)))
> > > > > > + continue;
> > > > > > + if (args.device_caps && (args.device_caps & cap.device_caps) != args.device_caps)
> > > > > > + continue;
> > > > > > + fprintf(stdout, "%s\n", devnode);
> > > > > > + } while (vid);
> > > > > > + free_media_devices(md);
> > > > > > + return 0;
> > > > > > +}
> > > > > > diff --git a/v4l-utils.spec.in b/v4l-utils.spec.in
> > > > > > index 67bdca57ae92..ab15286b039b 100644
> > > > > > --- a/v4l-utils.spec.in
> > > > > > +++ b/v4l-utils.spec.in
> > > > > > @@ -159,6 +159,7 @@ gtk-update-icon-cache %{_datadir}/icons/hicolor &>/dev/null || :
> > > > > > %{_bindir}/ivtv-ctl
> > > > > > %{_bindir}/v4l2-ctl
> > > > > > %{_bindir}/v4l2-sysfs-path
> > > > > > +%{_bindir}/v4l2-get-device
> > > > > > %{_mandir}/man1/ir-keytable.1*
> > > > > > %{_mandir}/man1/ir-ctl.1*
> > > > > >
> > > > > >
> > > > >
> > > > > Regards,
> > > > >
> > > > > Hans
