<div dir="ltr"><div dir="ltr">Hi Kieran,</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 9 Dec 2021 at 10:25, Kieran Bingham <<a href="mailto:kieran.bingham@ideasonboard.com">kieran.bingham@ideasonboard.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Quoting Naushir Patuck (2021-12-09 10:07:43)<br>
> Hi Kieran,<br>
> <br>
> Thanks for your feedback.<br>
> <br>
> On Thu, 9 Dec 2021 at 09:39, Kieran Bingham <<a href="mailto:kieran.bingham@ideasonboard.com" target="_blank">kieran.bingham@ideasonboard.com</a>><br>
> wrote:<br>
> <br>
> > Quoting Naushir Patuck (2021-12-08 15:15:27)<br>
> > > This change will allow the pipeline handler to enumerate and control<br>
> > Video<br>
> > > Mux or Bridge devices that may be attached between sensors and a<br>
> > particular<br>
> > > Unicam instance. Cascaded mux or bridge devices are also handled.<br>
> > ><br>
> > > A new member function enumerateVideoDevices(), called from<br>
> > registerCamera(), is<br>
> > > used to identify and open all mux and bridge subdevices present in the<br>
> > > sensor -> Unicam link.<br>
> > ><br>
> > > Relevent links are enabled/disabled and pad formats correctly set in<br>
> > configure()<br>
> > > before the camera is started.<br>
> > ><br>
> > > Signed-off-by: Naushir Patuck <<a href="mailto:naush@raspberrypi.com" target="_blank">naush@raspberrypi.com</a>><br>
> > > ---<br>
> > > .../pipeline/raspberrypi/raspberrypi.cpp | 78 +++++++++++++++++++<br>
> > > 1 file changed, 78 insertions(+)<br>
> > ><br>
> > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> > b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> > > index 756878c70036..ca176ecb40ec 100644<br>
> > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp<br>
> > > @@ -12,6 +12,7 @@<br>
> > > #include <mutex><br>
> > > #include <queue><br>
> > > #include <unordered_set><br>
> > > +#include <utility><br>
> > ><br>
> > > #include <libcamera/base/shared_fd.h><br>
> > > #include <libcamera/base/utils.h><br>
> > > @@ -220,6 +221,11 @@ public:<br>
> > > std::vector<RPi::Stream *> streams_;<br>
> > > /* Stores the ids of the buffers mapped in the IPA. */<br>
> > > std::unordered_set<unsigned int> ipaBuffers_;<br>
> > > + /*<br>
> > > + * Stores a cascade of Video Mux or Bridge devices between the<br>
> > sensor and<br>
> > > + * Unicam together with media link across the entities.<br>
> > > + */<br>
> > > + std::vector<std::pair<std::unique_ptr<V4L2Subdevice>, MediaLink<br>
> > *>> bridgeDevices_;<br>
> > ><br>
> > > /* DMAHEAP allocation helper. */<br>
> > > RPi::DmaHeap dmaHeap_;<br>
> > > @@ -311,6 +317,7 @@ private:<br>
> > > }<br>
> > ><br>
> > > int registerCamera(MediaDevice *unicam, MediaDevice *isp,<br>
> > MediaEntity *sensorEntity);<br>
> > > + void enumerateVideoDevices(RPiCameraData *data, MediaLink *link);<br>
> > > int queueAllBuffers(Camera *camera);<br>
> > > int prepareBuffers(Camera *camera);<br>
> > > void freeBuffers(Camera *camera);<br>
> > > @@ -868,6 +875,25 @@ int PipelineHandlerRPi::configure(Camera *camera,<br>
> > CameraConfiguration *config)<br>
> > > */<br>
> > > data->properties_.set(properties::ScalerCropMaximum,<br>
> > data->sensorInfo_.analogCrop);<br>
> > ><br>
> > > + /* Setup the Video Mux/Bridge entities. */<br>
> > > + for (auto &[device, link] : data->bridgeDevices_) {<br>
> > > + /* Start by disabling all the sink pad links on the<br>
> > devices in the cascade. */<br>
> > > + for (const MediaPad *p : device->entity()->pads()) {<br>
> > > + if (!(p->flags() & MEDIA_PAD_FL_SINK))<br>
> > > + continue;<br>
> > > +<br>
> > > + for (MediaLink *l : p->links())<br>
> > > + l->setEnabled(false);<br>
> > > + }<br>
> > > +<br>
> > > + /* Finally enable the link, and setup the pad format. */<br>
> > > + link->setEnabled(true);<br>
> ><br>
> > Isn't this going to enable /all/ bridge links in the cascade<br>
> > incorrectly?<br>
> ><br>
> ><br>
> > ┌──────────┐<br>
> > │ Unicam │<br>
> > └─────▲────┘<br>
> > │<br>
> > ┌───┴───┐<br>
> > │ Mux ◄───────┐<br>
> > └──▲────┘ │<br>
> > │ │<br>
> > ┌─────┴───┐ ┌───┴───┐<br>
> > │ Sensor1 │ │ Mux │◄──┐<br>
> > └─────────┘ └─▲─────┘ │<br>
> > │ │<br>
> > ┌───────┴─┐ ┌───┴─────┐<br>
> > │ Sensor2 │ │ Sensor3 │<br>
> > └─────────┘ └─────────┘<br>
> ><br>
> > In that 'use case' we're now iterating over all bridges and enabling<br>
> > their link, I think which means we've just enabled both muxes,<br>
> > immediately after disabling them - even for Sensor1?<br>
> ><br>
> > Maybe I've mis-understood it, but I thought there would be something<br>
> > that would start at the desired sensor, and walk up the links to the<br>
> > unicam enabling those links (and only those) as it went up?<br>
> ><br>
> > The walk only has to be done once too, so perhaps a per-camera(sensor)<br>
> > vector of links to iterate and enable?<br>
> ><br>
> > Or maybe I'm missing the separation between the bridgeDevices_ and the<br>
> > per-camera instances. But if that's already happening, I can't then see<br>
> > how each camera data clears all the bridges used by other cameras...<br>
> ><br>
> <br>
> Let me explain my intention, and you can then tell me if the code does<br>
> what I think it does :-)<br>
> <br>
> Each sensor (Sensor{1,2,3}) will register its own Camera object, and<br>
> in that object bridgeDevices_ will store the cascade of muxes between<br>
> the sensor and the Unicam port. So, for Sensor1, we store only 1 mux,<br>
> and Sensor{2,3} will store both muxes. Together with the mux device,<br>
> we also store the entity to entity links.<br>
> <br>
> The above code goes through those stored entities, first disabling *all*<br>
> links on each device in the chain, and then selectively enabling<br>
> the specific links that are stored in bridgeDevices_ to link sensor<br>
> to Unicam across all intermedia muxes. If Sensor1 is used, this<br>
> does mean that the Sensor{2,3} -> Mux links might not change<br>
> state but the Mux to Mux link will be disabled. Similarly, if we are<br>
> driving<br>
> Sensor3, the Sensor{1,2} -> Mux link will be disabled.<br>
<br>
I think I see the obvious part I missed ;-)<br>
<br>
It doesn't matter what configuration Mux2 has as long as Mux1 only has<br>
Sensor1 link enabled!<br>
<br>
It might help to document that in the comments somehow somewhere?<br>
Particularly now that you've already written the explanation to me -<br>
perhaps it should be a block comment above enumerateVideoDevices.<br>
<br>
Feel free to take or add the ascii diagram, I think more pictures in<br>
our documentation are always helpful. It's really easy to make those<br>
block diagrams in ascii art at <a href="https://asciiflow.com" rel="noreferrer" target="_blank">https://asciiflow.com</a>.<br></blockquote><div><br></div><div>Sure, I'll add some comments through the code explaining it in more detail.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
<br>
> ><br>
> > > + const MediaPad *srcPad = link->sink();<br>
> > > + ret = device->setFormat(srcPad->index(), &sensorFormat);<br>
> ><br>
> > This assignment of ret is in a loop, so earlier failures are going to<br>
> > get ignored, unchecked.<br>
> ><br>
> <br>
> This should not matter, as ret is only used in the loop to count successful<br>
> camera registrations. The return value from match() will be false only if<br>
> 0 cameras were registered.<br>
<br>
So should we not even assign it?<br>
Do we need to report a warning if it failed to set the format?<br>
<br>
But aren't we here in configure() setting the format of the device to<br>
propogate the format?<br>
<br>
If we fail to setFormat in that case, then I think we should be saying<br>
the configure() call failed?<br></blockquote><div><br></div><div>Oops, my mistake. I misread your original comment and what bit of</div><div>code it refers to! This ret value *is* used for the return path, and must</div><div>be accounted for correctly as it is set in a loop! I'll fix this in the next</div><div>revision.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
<br>
<br>
> <br>
> <br>
> ><br>
> > > + LOG(RPI, Info) << "Configured media link on device " <<<br>
> > device->entity()->name()<br>
> > > + << " at pad " << srcPad->index();<br>
> > > + }<br>
> > > +<br>
> > > return ret;<br>
> > > }<br>
> > ><br>
> > > @@ -1098,6 +1124,13 @@ int<br>
> > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me<br>
> > > if (data->sensor_->init())<br>
> > > return -EINVAL;<br>
> > ><br>
> > > + /*<br>
> > > + * Enumerate all the Video Mux/Bridge devices across the sensor<br>
> > -> unicam<br>
> > > + * link. There may be a cascade of devices in this link!<br>
> > > + */<br>
> > > + MediaLink *link = sensorEntity->getPadByIndex(0)->links()[0];<br>
> > > + enumerateVideoDevices(data.get(), link);<br>
> > > +<br>
> > > data->sensorFormats_ = populateSensorFormats(data->sensor_);<br>
> > ><br>
> > > ipa::RPi::SensorConfig sensorConfig;<br>
> > > @@ -1224,6 +1257,51 @@ int<br>
> > PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me<br>
> > > return 0;<br>
> > > }<br>
> > ><br>
> > > +void PipelineHandlerRPi::enumerateVideoDevices(RPiCameraData *data,<br>
> > MediaLink *link)<br>
> > > +{<br>
> > > + const MediaPad *sinkPad = link->sink();<br>
> > > + const MediaEntity *entity = sinkPad->entity();<br>
> > > + bool unicamFound = false;<br>
> > > +<br>
> > > + /* We only deal with Video Mux and Bridge devices in cascade. */<br>
> > > + if (entity->function() != MEDIA_ENT_F_VID_MUX &&<br>
> > > + entity->function() != MEDIA_ENT_F_VID_IF_BRIDGE)<br>
> > > + return;<br>
> > > +<br>
> > > + LOG(RPI, Info) << "Found video mux device " << entity->name()<br>
> > > + << " linked to sink pad " << sinkPad->index();<br>
> > > +<br>
> > > +<br>
> > data->bridgeDevices_.emplace_back(std::make_unique<V4L2Subdevice>(entity),<br>
> > link);<br>
> > > + data->bridgeDevices_.back().first->open();<br>
> ><br>
> > Going through the above, I can't help but wonder if the bridgeDevices_<br>
> > should be stored as a single instance in the Pipeline handler (not each<br>
> > CameraData, we have one CameraData per camera right? if so, how does<br>
> > camera3 disable all the links? does it know about every path?)<br>
> ><br>
> <br>
> From my description earlier, bridgeDevices_ must be stored in the<br>
> CameraData, as<br>
> it lists the devices in the path between the sensor and Unicam. And this<br>
> is unique<br>
> per-sensor. Again, this does mean that if we are using Sensor1, links for<br>
> Sensor{2,3}<br>
> -> Mux are not changed, but the Mux->Mux link will be disabled. Do you<br>
> think<br>
> that may not be appropriate leaving them enabled?<br>
<br>
I missed that, and now it's obvious. If the first mux is only pointing<br>
to Sensor1, then indeed it doesn't matter what mux2 is configured to<br>
link to...<br>
<br>
So I think that's ok.<br>
<br>
> <br>
> Please shout if this doesn't make sense, and something simpler might<br>
> equally work :-)<br>
<br>
It's all fine until someone adds a crossbar perhaps that might make it<br>
possible to do more crazy things ;-)<br>
<br>
But we don't need to worry about that now I dont' think.<br>
<br>
I think I'm still concerned about that ret during the loop in<br>
configure(). But with that resolved:<br>
<br>
Reviewed-by: Kieran Bingham <<a href="mailto:kieran.bingham@ideasonboard.com" target="_blank">kieran.bingham@ideasonboard.com</a>><br>
<br>
> Cheers,<br>
> Naush<br>
> <br>
> <br>
> <br>
> ><br>
> ><br>
> > > +<br>
> > > + for (const MediaPad *pad : entity->pads()) {<br>
> > > + /*<br>
> > > + * Iterate through all the sink pads down the cascade to<br>
> > find any<br>
> > > + * other Video Mux and Bridge devices.<br>
> > > + */<br>
> > > + if (!(pad->flags() & MEDIA_PAD_FL_SOURCE))<br>
> > > + continue;<br>
> > > +<br>
> > > + for (MediaLink *l : pad->links()) {<br>
> > > + enumerateVideoDevices(data, l);<br>
> > > + if (l->sink()->entity()->name() ==<br>
> > "unicam-image")<br>
> > > + unicamFound = true;<br>
> > > + }<br>
> > > + }<br>
> > > +<br>
> > > + /* This identifies the end of our entity enumeration recursion.<br>
> > */<br>
> > > + if (link->source()->entity()->function() ==<br>
> > MEDIA_ENT_F_CAM_SENSOR) {<br>
> > > + /*<br>
> > > + * If Unicam is not at the end of this cascade, we cannot<br>
> > configure<br>
> > > + * this topology automatically, so remove all entity<br>
> > references.<br>
> > > + */<br>
> > > + if (!unicamFound) {<br>
> > > + LOG(RPI, Warning) << "Cannot automatically<br>
> > configure this MC topology!";<br>
> > > + data->bridgeDevices_.clear();<br>
> > > + }<br>
> > > + }<br>
> > > +}<br>
> > > +<br>
> > > int PipelineHandlerRPi::queueAllBuffers(Camera *camera)<br>
> > > {<br>
> > > RPiCameraData *data = cameraData(camera);<br>
> > > --<br>
> > > 2.25.1<br>
> > ><br>
> ><br>
</blockquote></div></div>