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

[Laurent Pinchart]

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 :-)

> >> +			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,

Laurent Pinchart