[libcamera-devel] [PATCH] pipeline: raspberrypi: Iterate over all Unicam instances in match()
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Fri Mar 10 11:33:21 CET 2023
Hi Naush,
On Fri, Mar 10, 2023 at 10:22:01AM +0000, Naushir Patuck wrote:
> One more thing....
>
> On Fri, 10 Mar 2023 at 10:01, Naushir Patuck wrote:
> > On Thu, 9 Mar 2023 at 10:02, Laurent Pinchart wrote:
> >> On Thu, Mar 09, 2023 at 08:04:47AM +0000, Naushir Patuck wrote:
> >> > On Thu, 9 Mar 2023 at 01:14, Laurent Pinchart wrote:
> >> >
> >> > > Hi Naush,
> >> > >
> >> > > Thank you for the patch.
> >> > >
> >> > > I know this has been merged, but I've noticed a few issues, which can be
> >> > > fixed in further patches.
> >> > >
> >> > > On Fri, Feb 24, 2023 at 07:30:23AM +0000, Naushir Patuck via libcamera-devel wrote:
> >> > > >
> >> > > > On Raspberry Pi Compute Module platforms, it is possible to attach a
> >> > > > single camera device only to the secondary Unicam port. The current
> >> > > > logic of PipelineHandlerRPi::match() will return a failure during
> >> > > > enumeration of the first Unicam media device (due to no sensor attached,
> >> > > > or sensor failure) and thus the second Unicam media device will never be
> >> > > > enumerated.
> >> > > >
> >> > > > Fix this by looping over all Unicam instances in PipelineHandlerRPi::match()
> >> > > > until a camera is correctly registered, or return a failure otherwise.
> >> > > >
> >> > > > Reported-on: https://github.com/raspberrypi/libcamera/issues/44
> >> > > > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> >> > > > ---
> >> > > > .../pipeline/raspberrypi/raspberrypi.cpp | 67 +++++++++++--------
> >> > > > 1 file changed, 40 insertions(+), 27 deletions(-)
> >> > > >
> >> > > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> >> > > > index 841209548350..ef01b7e166ba 100644
> >> > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> >> > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> >> > > > @@ -1246,41 +1246,54 @@ int PipelineHandlerRPi::queueRequestDevice(Camera *camera, Request *request)
> >> > > >
> >> > > > bool PipelineHandlerRPi::match(DeviceEnumerator *enumerator)
> >> > > > {
> >> > > > - DeviceMatch unicam("unicam");
> >> > > > - MediaDevice *unicamDevice = acquireMediaDevice(enumerator, unicam);
> >> > > > + constexpr unsigned int numUnicamDevices = 2;
> >> > >
> >> > > Constants should start with a k prefix, that is kNumUnicamDevices.
> >> > >
> >> > > >
> >> > > > - if (!unicamDevice) {
> >> > > > - LOG(RPI, Debug) << "Unable to acquire a Unicam instance";
> >> > > > - return false;
> >> > > > - }
> >> > > > + /*
> >> > > > + * Loop over all Unicam instances, but return out once a match is found.
> >> > > > + * This is to ensure we correctly enumrate the camera when an instance
> >> > > > + * of Unicam has registered with media controller, but has not registered
> >> > > > + * device nodes due to a sensor subdevice failure.
> >> > > > + */
> >> > > > + for (unsigned int i = 0; i < numUnicamDevices; i++) {
> >> > > > + DeviceMatch unicam("unicam");
> >> > > > + MediaDevice *unicamDevice = acquireMediaDevice(enumerator, unicam);
> >> > > >
> >> > > > - DeviceMatch isp("bcm2835-isp");
> >> > > > - MediaDevice *ispDevice = acquireMediaDevice(enumerator, isp);
> >> > > > + if (!unicamDevice) {
> >> > > > + LOG(RPI, Debug) << "Unable to acquire a Unicam instance";
> >> > > > + continue;
> >> > >
> >> > > This looks weird, if the unicam device can't be acquired, I don't see
> >> > > how the next iteration of the loop could successfully acquire another
> >> > > instance. I would thus break here.
> >> >
> >> > This is probably me not understanding how the media device enumeration stuff
> >> > works, but I thought the continue would be needed for situations where we want
> >> > simultaneous dual cameras running in separate processes. For example, process 0
> >> > acquires "Unicam 0" and starts running as normal. Process 1 starts and goes
> >> > through match() where "Unicam 0" still exists in the entity list, but fails to
> >> > acquire because it is locked by process 0. So we have to move on to "Unicam 1"
> >> > which is acquired correctly for process 1. Is that understanding wrong?
> >>
> >> The minimal inter-process locking support in libcamera only operates
> >> when trying to acquire a *camera* with Camera::acquire(). The
> >> acquireMediaDevice() function is a bit confusing, its name refers to the
> >> pipeline handler acquiring a MediaDevice from the DeviceEnumerator,
> >> guaranteeing that the pipeline handler gets ownership of the media
> >> device and no other pipeline handler *in the same process* will be able
> >> to acquire it. Two processes running libcamera will both get "Unicam 0"
> >> in the first iteration of the loop.
> >
> > For my clarification, so process 1 will still acquire Unicam 0, but when it
> > comes to camera.start(), will fail since process 0 will have Unicam 0 running in
> > its process. Is that right?
> >
> >> > > > + }
> >> > > >
> >> > > > - if (!ispDevice) {
> >> > > > - LOG(RPI, Debug) << "Unable to acquire ISP instance";
> >> > > > - return false;
> >> > > > - }
> >> > > > + DeviceMatch isp("bcm2835-isp");
> >> > > > + MediaDevice *ispDevice = acquireMediaDevice(enumerator, isp);
> >> > > >
> >> > > > - /*
> >> > > > - * The loop below is used to register multiple cameras behind one or more
> >> > > > - * video mux devices that are attached to a particular Unicam instance.
> >> > > > - * Obviously these cameras cannot be used simultaneously.
> >> > > > - */
> >> > > > - unsigned int numCameras = 0;
> >> > > > - for (MediaEntity *entity : unicamDevice->entities()) {
> >> > > > - if (entity->function() != MEDIA_ENT_F_CAM_SENSOR)
> >> > > > + if (!ispDevice) {
> >> > > > + LOG(RPI, Debug) << "Unable to acquire ISP instance";
> >> > > > continue;
> >> > >
> >> > > Shouldn't you release the unicam device in this case ? I think it would
> >> > > be better to first loop over unicam instances, ignoring any instance
> >> > > than has no connected camera sensor, and then, if an instance with a
> >> > > connected sensor is found, acquire an ISP instance.
>
> Actually, moving the ISP acquire into the inner loop would be the wrong thing to
> do. The inner loop is to identify multiple cameras attached to a single Unicam
> port through a mux/bridge chip. As such, only a single sensor can be active at
> any time, and only a single ISP can service them. So I think the ISP acquiring
> code is in the right place.
Yes, but that's not what I meant :-)
foreach (unicam instances) {
unicam = acquireMediaDevice(instance);
if (!unicam)
/* We've exhausted all unicam instances */
return false;
if (unicam instance has connected source)
break;
}
DeviceMatch isp("bcm2835-isp");
MediaDevice *ispDevice = acquireMediaDevice(enumerator, isp);
if (!ispDevice)
return false;
> >> > I think we discussed this briefly in the github comments. There is no
> >> > compliment releaseMediaDevice() call that I can use to release the device.
> >>
> >> It's an issue indeed. The design idea was to release all acquired media
> >> devices automatically when the match() function returns false, but that
> >> doesn't allow releasing media device that have been acquired and turned
> >> out not to be needed.
> >>
> >> In this specific case, if you acquire a unicam instance that has no
> >> connected sensor, it's fine if it stays acquired as no other pipeline
> >> handler instance would be able to use it for a meaningful purpose
> >> anyway, but in general this is something we should probably fix.
> >>
> >> > Regarding the second part of the comment, yes, I could move the isp acquire bit
> >> > into the for (unicamDevice->entities()) loop to optimise this a bit.
> >>
> > >
> >> > > > + }
> >> > > >
> >> > > > - int ret = registerCamera(unicamDevice, ispDevice, entity);
> >> > > > - if (ret)
> >> > > > - LOG(RPI, Error) << "Failed to register camera "
> >> > > > - << entity->name() << ": " << ret;
> >> > > > - else
> >> > > > - numCameras++;
> >> > > > + /*
> >> > > > + * The loop below is used to register multiple cameras behind one or more
> >> > > > + * video mux devices that are attached to a particular Unicam instance.
> >> > > > + * Obviously these cameras cannot be used simultaneously.
> >> > > > + */
> >> > > > + unsigned int numCameras = 0;
> >> > > > + for (MediaEntity *entity : unicamDevice->entities()) {
> >> > > > + if (entity->function() != MEDIA_ENT_F_CAM_SENSOR)
> >> > > > + continue;
> >> > > > +
> >> > > > + int ret = registerCamera(unicamDevice, ispDevice, entity);
> >> > > > + if (ret)
> >> > > > + LOG(RPI, Error) << "Failed to register camera "
> >> > > > + << entity->name() << ": " << ret;
> >> > > > + else
> >> > > > + numCameras++;
> >> > > > + }
> >> > > > +
> >> > > > + if (numCameras)
> >> > > > + return true;
> >> > > > }
> >> > > >
> >> > > > - return !!numCameras;
> >> > > > + return false;
> >> > > > }
> >> > > >
> >> > > > void PipelineHandlerRPi::releaseDevice(Camera *camera)
--
Regards,
Laurent Pinchart
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