Resurrecting this thread, since this functionality would be really useful :-)
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.
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
>
>
