[libcamera-devel] [PATCH] libcamera: device_enumerator: Don't stop if one device fails

[Kieran Bingham]

Hi Laurent,

On 17/02/2020 10:43, Laurent Pinchart wrote:
> Hi Kieran,
> 
> On Mon, Feb 17, 2020 at 10:41:23AM +0000, Kieran Bingham wrote:
>> On 17/02/2020 08:23, Kieran Bingham wrote:
>>> On 14/02/2020 12:37, Laurent Pinchart wrote:
>>>> If one device fails to enumerate, which isn't supposed to happen under
>>>> normal conditions, both the sysfs and the udev enumerators stop
>>>> enumeration of further devices. This potentially prevents working
>>>> devices from being detected and handled. Fix it by skipping the faulty
>>>> device.
>>>
>>> Thank you,
>>>
>>> This does indeed allow the system to continue and function with the
>>> available cameras.
>>>
>>> Interestingly, in the particular case that I was investigating - it
>>> wasn't the newly added device that failed ... it was the existing camera
>>> interface.
>>>
>>> That can be investigated separately.
>>>
>>>> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>>
>> Thanks, indeed this now continues to function and produces an
>> appropriate message for the failing device components:
>>
>>> [2:20:54.425174891] [3209]  ERR MediaDevice media_device.cpp:242 Failed to enumerate topology: Bad address
>>> [2:20:54.425281647] [3209] INFO DeviceEnumerator device_enumerator.cpp:217 Unable to populate media device /dev/media0 (Invalid argument), skipping
>>> [2:20:54.425393663] [3209] WARN DeviceEnumerator device_enumerator_udev.cpp:149 Failed to add device for '/sys/devices/platform/soc/fe801000.csi/media0', skipping
>>> Using camera VF0520 Live! Cam Sync: VF0520 L
>>
>> Tested-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>
>> And with one small comment considered below:
>>
>> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>
>>>> ---
>>>>  src/libcamera/device_enumerator_sysfs.cpp | 15 +++++++--------
>>>>  src/libcamera/device_enumerator_udev.cpp  |  8 +++++---
>>>>  2 files changed, 12 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/src/libcamera/device_enumerator_sysfs.cpp b/src/libcamera/device_enumerator_sysfs.cpp
>>>> index ad26affb38a3..bde736226f95 100644
>>>> --- a/src/libcamera/device_enumerator_sysfs.cpp
>>>> +++ b/src/libcamera/device_enumerator_sysfs.cpp
>>>> @@ -33,7 +33,6 @@ int DeviceEnumeratorSysfs::enumerate()
>>>>  {
>>>>  	struct dirent *ent;
>>>>  	DIR *dir;
>>>> -	int ret = 0;
>>>>  
>>>>  	static const char * const sysfs_dirs[] = {
>>>>  		"/sys/subsystem/media/devices",
>>>> @@ -74,14 +73,14 @@ int DeviceEnumeratorSysfs::enumerate()
>>>>  		}
>>>>  
>>>>  		std::shared_ptr<MediaDevice> media = createDevice(devnode);
>>>> -		if (!media) {
>>>> -			ret = -ENODEV;
>>>> -			break;
>>>> -		}
>>>> +		if (!media)
>>>> +			continue;
>>>>  
>>>>  		if (populateMediaDevice(media) < 0) {
>>>> -			ret = -ENODEV;
>>>> -			break;
>>>> +			LOG(DeviceEnumerator, Warning)
>>>> +				<< "Failed to populate media device /dev/media"
>>>> +				<< idx << ", skipping";
>>
>> Shouldn't this use something like media->deviceNode() ?
>>
>> (Perhaps even printing media->driver() and media->model for guidance too?)
> 
> That's a good idea, I'll submit a v2 for you to test :-)

There's also the local variable available which was used to construct
the MediaDevice; - devnode;

But getting the strings from the MediaDevice and being more verbose
about the failure seems a bit more beneficial all the same.

--
Kieran


> 
>>>> +			continue;
>>>>  		}
>>>>  
>>>>  		addDevice(media);
>>>> @@ -89,7 +88,7 @@ int DeviceEnumeratorSysfs::enumerate()
>>>>  
>>>>  	closedir(dir);
>>>>  
>>>> -	return ret;
>>>> +	return 0;
>>>>  }
>>>>  
>>>>  int DeviceEnumeratorSysfs::populateMediaDevice(const std::shared_ptr<MediaDevice> &media)
>>>> diff --git a/src/libcamera/device_enumerator_udev.cpp b/src/libcamera/device_enumerator_udev.cpp
>>>> index b2c5fd221dcd..3837aaf97e6a 100644
>>>> --- a/src/libcamera/device_enumerator_udev.cpp
>>>> +++ b/src/libcamera/device_enumerator_udev.cpp
>>>> @@ -145,10 +145,12 @@ int DeviceEnumeratorUdev::enumerate()
>>>>  			goto done;
>>>>  		}
>>>>  
>>>> -		ret = addUdevDevice(dev);
>>>> +		if (addUdevDevice(dev) < 0)
>>>> +			LOG(DeviceEnumerator, Warning)
>>>> +				<< "Failed to add device for '"
>>>> +				<< syspath << "', skipping";
>>>> +
>>>>  		udev_device_unref(dev);
>>>> -		if (ret < 0)
>>>> -			break;
>>>>  	}
>>>>  
>>>>  done:
> 

-- 
Regards
--
Kieran