[libcamera-devel] [PATCH v2 2/2] pipeline: raspberrypi: Add support for Video Mux and Bridge devices
Naushir Patuck
naush at raspberrypi.com
Thu Dec 9 11:29:21 CET 2021
Hi Kieran,
On Thu, 9 Dec 2021 at 10:25, Kieran Bingham <kieran.bingham at ideasonboard.com>
wrote:
> Quoting Naushir Patuck (2021-12-09 10:07:43)
> > Hi Kieran,
> >
> > Thanks for your feedback.
> >
> > On Thu, 9 Dec 2021 at 09:39, Kieran Bingham <
> kieran.bingham at ideasonboard.com>
> > wrote:
> >
> > > Quoting Naushir Patuck (2021-12-08 15:15:27)
> > > > This change will allow the pipeline handler to enumerate and control
> > > Video
> > > > Mux or Bridge devices that may be attached between sensors and a
> > > particular
> > > > Unicam instance. Cascaded mux or bridge devices are also handled.
> > > >
> > > > A new member function enumerateVideoDevices(), called from
> > > registerCamera(), is
> > > > used to identify and open all mux and bridge subdevices present in
> the
> > > > sensor -> Unicam link.
> > > >
> > > > Relevent links are enabled/disabled and pad formats correctly set in
> > > configure()
> > > > before the camera is started.
> > > >
> > > > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> > > > ---
> > > > .../pipeline/raspberrypi/raspberrypi.cpp | 78
> +++++++++++++++++++
> > > > 1 file changed, 78 insertions(+)
> > > >
> > > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > index 756878c70036..ca176ecb40ec 100644
> > > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > > @@ -12,6 +12,7 @@
> > > > #include <mutex>
> > > > #include <queue>
> > > > #include <unordered_set>
> > > > +#include <utility>
> > > >
> > > > #include <libcamera/base/shared_fd.h>
> > > > #include <libcamera/base/utils.h>
> > > > @@ -220,6 +221,11 @@ public:
> > > > std::vector<RPi::Stream *> streams_;
> > > > /* Stores the ids of the buffers mapped in the IPA. */
> > > > std::unordered_set<unsigned int> ipaBuffers_;
> > > > + /*
> > > > + * Stores a cascade of Video Mux or Bridge devices between
> the
> > > sensor and
> > > > + * Unicam together with media link across the entities.
> > > > + */
> > > > + std::vector<std::pair<std::unique_ptr<V4L2Subdevice>,
> MediaLink
> > > *>> bridgeDevices_;
> > > >
> > > > /* DMAHEAP allocation helper. */
> > > > RPi::DmaHeap dmaHeap_;
> > > > @@ -311,6 +317,7 @@ private:
> > > > }
> > > >
> > > > int registerCamera(MediaDevice *unicam, MediaDevice *isp,
> > > MediaEntity *sensorEntity);
> > > > + void enumerateVideoDevices(RPiCameraData *data, MediaLink
> *link);
> > > > int queueAllBuffers(Camera *camera);
> > > > int prepareBuffers(Camera *camera);
> > > > void freeBuffers(Camera *camera);
> > > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera
> *camera,
> > > CameraConfiguration *config)
> > > > */
> > > > data->properties_.set(properties::ScalerCropMaximum,
> > > data->sensorInfo_.analogCrop);
> > > >
> > > > + /* Setup the Video Mux/Bridge entities. */
> > > > + for (auto &[device, link] : data->bridgeDevices_) {
> > > > + /* Start by disabling all the sink pad links on the
> > > devices in the cascade. */
> > > > + for (const MediaPad *p : device->entity()->pads()) {
> > > > + if (!(p->flags() & MEDIA_PAD_FL_SINK))
> > > > + continue;
> > > > +
> > > > + for (MediaLink *l : p->links())
> > > > + l->setEnabled(false);
> > > > + }
> > > > +
> > > > + /* Finally enable the link, and setup the pad
> format. */
> > > > + link->setEnabled(true);
> > >
> > > Isn't this going to enable /all/ bridge links in the cascade
> > > incorrectly?
> > >
> > >
> > > ┌──────────┐
> > > │ Unicam │
> > > └─────▲────┘
> > > │
> > > ┌───┴───┐
> > > │ Mux ◄───────┐
> > > └──▲────┘ │
> > > │ │
> > > ┌─────┴───┐ ┌───┴───┐
> > > │ Sensor1 │ │ Mux │◄──┐
> > > └─────────┘ └─▲─────┘ │
> > > │ │
> > > ┌───────┴─┐ ┌───┴─────┐
> > > │ Sensor2 │ │ Sensor3 │
> > > └─────────┘ └─────────┘
> > >
> > > In that 'use case' we're now iterating over all bridges and enabling
> > > their link, I think which means we've just enabled both muxes,
> > > immediately after disabling them - even for Sensor1?
> > >
> > > Maybe I've mis-understood it, but I thought there would be something
> > > that would start at the desired sensor, and walk up the links to the
> > > unicam enabling those links (and only those) as it went up?
> > >
> > > The walk only has to be done once too, so perhaps a per-camera(sensor)
> > > vector of links to iterate and enable?
> > >
> > > Or maybe I'm missing the separation between the bridgeDevices_ and the
> > > per-camera instances. But if that's already happening, I can't then see
> > > how each camera data clears all the bridges used by other cameras...
> > >
> >
> > Let me explain my intention, and you can then tell me if the code does
> > what I think it does :-)
> >
> > Each sensor (Sensor{1,2,3}) will register its own Camera object, and
> > in that object bridgeDevices_ will store the cascade of muxes between
> > the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,
> > and Sensor{2,3} will store both muxes. Together with the mux device,
> > we also store the entity to entity links.
> >
> > The above code goes through those stored entities, first disabling *all*
> > links on each device in the chain, and then selectively enabling
> > the specific links that are stored in bridgeDevices_ to link sensor
> > to Unicam across all intermedia muxes. If Sensor1 is used, this
> > does mean that the Sensor{2,3} -> Mux links might not change
> > state but the Mux to Mux link will be disabled. Similarly, if we are
> > driving
> > Sensor3, the Sensor{1,2} -> Mux link will be disabled.
>
> I think I see the obvious part I missed ;-)
>
> It doesn't matter what configuration Mux2 has as long as Mux1 only has
> Sensor1 link enabled!
>
> It might help to document that in the comments somehow somewhere?
> Particularly now that you've already written the explanation to me -
> perhaps it should be a block comment above enumerateVideoDevices.
>
> Feel free to take or add the ascii diagram, I think more pictures in
> our documentation are always helpful. It's really easy to make those
> block diagrams in ascii art at https://asciiflow.com.
>
Sure, I'll add some comments through the code explaining it in more detail.
>
>
> > >
> > > > + const MediaPad *srcPad = link->sink();
> > > > + ret = device->setFormat(srcPad->index(),
> &sensorFormat);
> > >
> > > This assignment of ret is in a loop, so earlier failures are going to
> > > get ignored, unchecked.
> > >
> >
> > This should not matter, as ret is only used in the loop to count
> successful
> > camera registrations. The return value from match() will be false only
> if
> > 0 cameras were registered.
>
> So should we not even assign it?
> Do we need to report a warning if it failed to set the format?
>
> But aren't we here in configure() setting the format of the device to
> propogate the format?
>
> If we fail to setFormat in that case, then I think we should be saying
> the configure() call failed?
>
Oops, my mistake. I misread your original comment and what bit of
code it refers to! This ret value *is* used for the return path, and must
be accounted for correctly as it is set in a loop! I'll fix this in the next
revision.
>
>
>
> >
> >
> > >
> > > > + LOG(RPI, Info) << "Configured media link on device "
> <<
> > > device->entity()->name()
> > > > + << " at pad " << srcPad->index();
> > > > + }
> > > > +
> > > > return ret;
> > > > }
> > > >
> > > > @@ -1098,6 +1124,13 @@ int
> > > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice
> *isp, Me
> > > > if (data->sensor_->init())
> > > > return -EINVAL;
> > > >
> > > > + /*
> > > > + * Enumerate all the Video Mux/Bridge devices across the
> sensor
> > > -> unicam
> > > > + * link. There may be a cascade of devices in this link!
> > > > + */
> > > > + MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];
> > > > + enumerateVideoDevices(data.get(), link);
> > > > +
> > > > data->sensorFormats_ = populateSensorFormats(data->sensor_);
> > > >
> > > > ipa::RPi::SensorConfig sensorConfig;
> > > > @@ -1224,6 +1257,51 @@ int
> > > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice
> *isp, Me
> > > > return 0;
> > > > }
> > > >
> > > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data,
> > > MediaLink *link)
> > > > +{
> > > > + const MediaPad *sinkPad = link->sink();
> > > > + const MediaEntity *entity = sinkPad->entity();
> > > > + bool unicamFound = false;
> > > > +
> > > > + /* We only deal with Video Mux and Bridge devices in
> cascade. */
> > > > + if (entity->function() != MEDIA_ENT_F_VID_MUX &&
> > > > + entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)
> > > > + return;
> > > > +
> > > > + LOG(RPI, Info) << "Found video mux device " << entity->name()
> > > > + << " linked to sink pad " << sinkPad->index();
> > > > +
> > > > +
> > >
> data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),
> > > link);
> > > > + data->bridgeDevices_.back().first->open();
> > >
> > > Going through the above, I can't help but wonder if the bridgeDevices_
> > > should be stored as a single instance in the Pipeline handler (not each
> > > CameraData, we have one CameraData per camera right? if so, how does
> > > camera3 disable all the links? does it know about every path?)
> > >
> >
> > From my description earlier, bridgeDevices_ must be stored in the
> > CameraData, as
> > it lists the devices in the path between the sensor and Unicam. And this
> > is unique
> > per-sensor. Again, this does mean that if we are using Sensor1, links
> for
> > Sensor{2,3}
> > -> Mux are not changed, but the Mux->Mux link will be disabled. Do you
> > think
> > that may not be appropriate leaving them enabled?
>
> I missed that, and now it's obvious. If the first mux is only pointing
> to Sensor1, then indeed it doesn't matter what mux2 is configured to
> link to...
>
> So I think that's ok.
>
> >
> > Please shout if this doesn't make sense, and something simpler might
> > equally work :-)
>
> It's all fine until someone adds a crossbar perhaps that might make it
> possible to do more crazy things ;-)
>
> But we don't need to worry about that now I dont' think.
>
> I think I'm still concerned about that ret during the loop in
> configure(). But with that resolved:
>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
> > Cheers,
> > Naush
> >
> >
> >
> > >
> > >
> > > > +
> > > > + for (const MediaPad *pad : entity->pads()) {
> > > > + /*
> > > > + * Iterate through all the sink pads down the
> cascade to
> > > find any
> > > > + * other Video Mux and Bridge devices.
> > > > + */
> > > > + if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))
> > > > + continue;
> > > > +
> > > > + for (MediaLink *l : pad->links()) {
> > > > + enumerateVideoDevices(data, l);
> > > > + if (l->sink()->entity()->name() ==
> > > "unicam-image")
> > > > + unicamFound = true;
> > > > + }
> > > > + }
> > > > +
> > > > + /* This identifies the end of our entity enumeration
> recursion.
> > > */
> > > > + if (link->source()->entity()->function() ==
> > > MEDIA_ENT_F_CAM_SENSOR) {
> > > > + /*
> > > > + * If Unicam is not at the end of this cascade, we
> cannot
> > > configure
> > > > + * this topology automatically, so remove all entity
> > > references.
> > > > + */
> > > > + if (!unicamFound) {
> > > > + LOG(RPI, Warning) << "Cannot automatically
> > > configure this MC topology!";
> > > > + data->bridgeDevices_.clear();
> > > > + }
> > > > + }
> > > > +}
> > > > +
> > > > int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> > > > {
> > > > RPiCameraData *data = cameraData(camera);
> > > > --
> > > > 2.25.1
> > > >
> > >
>
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