Quoting Daniel Scally (2022-06-06 18:04:40) > Hello all > > On 06/05/2022 22:15, Daniel Scally wrote: > > Creating links and registering subdev nodes during the .complete() > > callback has the unfortunate effect of preventing all cameras that > > connect to a notifier from working if any one of their drivers fails > > to probe. Moving the functionality from .complete() to .bound() allows > > those camera sensor drivers that did probe correctly to work regardless. > > > > Signed-off-by: Daniel Scally <djrscally@xxxxxxxxx> > > --- > > > > This results in v4l2_device_register_subdev_nodes() being called multiple times > > but since it's a no-op where the devnode exists already, I think that it's ok. > > > There ended up being a problem with this. If a camera sensor driver > registers a notifier via v4l2_async_register_subdev_sensor(), the > devnodes for any device that bound to that notifier (a lens controller > for example) would be created where v4l2_device_register_subdev_nodes() > is called by the ipu3-cio2 driver's .complete() callback. This is > because it won't be called until the lens controller's driver has > probed. On the other hand, if the lens controller's driver probes late > (after all the camera sensor drivers) then its devnodes _won't_ be > created because it'll miss the calls to > v4l2_device_register_subdev_nodes() when ipu3-cio2's .bound() is > triggered as their drivers probe. The effect of this is that we still > need a call to v4l2_device_register_subdev_nodes() in .complete() to > make sure we catch anything that's bound to a notifier registered by one > of the camera sensor drivers. This kinda defeats the purpose of the > patch as if an ISP has one sensor linked to a lens controller and one > one sensor without a lens controller, failure during probe of the driver > for the lens-less sensor will mean .complete() is never called, and so > the devnodes for the lens controller won't get created, and so the > sensor with a lens won't work properly anyway. > > > So - more thought needed on this I think. I still think it's the right > approach to refactor such that a failure in one sensor driver's probe > does not prevent any other sensors present from working provided _they_ > probe correctly, but I'm not sure the best way to achieve it now. As highlighted by Jacopo, I've proposed [0] that we talk more about this and really figure out a path to solving this (and planning to get it done I hope) at the media summit which will hopefully be held in Dublin. I last discussed this at the media summit in 2018! (life moves fast...) and my slides are at [1]. I guess we've had time to think about it all a bit more now since 2018, ... And certainly more usecases for this have come up since. Of course, ELCE/Summit is in September, so we can still work on this topic before then too! [0] https://lore.kernel.org/linux-media/165337661126.402452.10107682065782670158@Monstersaurus/ [1] https://docs.google.com/presentation/d/1Vdydt46QQtcYC0Sb7pn4qpL-ifnQdaCl0AkTSUIKE3U -- Kieran > > drivers/media/pci/intel/ipu3/ipu3-cio2-main.c | 65 +++++++------------ > > 1 file changed, 23 insertions(+), 42 deletions(-) > > > > diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c > > index 93cc0577b6db..6a1bcb20725d 100644 > > --- a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c > > +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c > > @@ -1387,7 +1387,10 @@ static int cio2_notifier_bound(struct v4l2_async_notifier *notifier, > > { > > struct cio2_device *cio2 = to_cio2_device(notifier); > > struct sensor_async_subdev *s_asd = to_sensor_asd(asd); > > + struct device *dev = &cio2->pci_dev->dev; > > struct cio2_queue *q; > > + unsigned int pad; > > + int ret; > > > > if (cio2->queue[s_asd->csi2.port].sensor) > > return -EBUSY; > > @@ -1398,7 +1401,26 @@ static int cio2_notifier_bound(struct v4l2_async_notifier *notifier, > > q->sensor = sd; > > q->csi_rx_base = cio2->base + CIO2_REG_PIPE_BASE(q->csi2.port); > > > > - return 0; > > + for (pad = 0; pad < q->sensor->entity.num_pads; pad++) > > + if (q->sensor->entity.pads[pad].flags & > > + MEDIA_PAD_FL_SOURCE) > > + break; > > + > > + if (pad == q->sensor->entity.num_pads) { > > + dev_err(dev, "failed to find src pad for %s\n", > > + q->sensor->name); > > + return -ENXIO; > > + } > > + > > + ret = media_create_pad_link(&q->sensor->entity, pad, &q->subdev.entity, > > + CIO2_PAD_SINK, 0); > > + if (ret) { > > + dev_err(dev, "failed to create link for %s\n", > > + q->sensor->name); > > + return ret; > > + } > > + > > + return v4l2_device_register_subdev_nodes(&cio2->v4l2_dev); > > } > > > > /* The .unbind callback */ > > @@ -1412,50 +1434,9 @@ static void cio2_notifier_unbind(struct v4l2_async_notifier *notifier, > > cio2->queue[s_asd->csi2.port].sensor = NULL; > > } > > > > -/* .complete() is called after all subdevices have been located */ > > -static int cio2_notifier_complete(struct v4l2_async_notifier *notifier) > > -{ > > - struct cio2_device *cio2 = to_cio2_device(notifier); > > - struct device *dev = &cio2->pci_dev->dev; > > - struct sensor_async_subdev *s_asd; > > - struct v4l2_async_subdev *asd; > > - struct cio2_queue *q; > > - unsigned int pad; > > - int ret; > > - > > - list_for_each_entry(asd, &cio2->notifier.asd_list, asd_list) { > > - s_asd = to_sensor_asd(asd); > > - q = &cio2->queue[s_asd->csi2.port]; > > - > > - for (pad = 0; pad < q->sensor->entity.num_pads; pad++) > > - if (q->sensor->entity.pads[pad].flags & > > - MEDIA_PAD_FL_SOURCE) > > - break; > > - > > - if (pad == q->sensor->entity.num_pads) { > > - dev_err(dev, "failed to find src pad for %s\n", > > - q->sensor->name); > > - return -ENXIO; > > - } > > - > > - ret = media_create_pad_link( > > - &q->sensor->entity, pad, > > - &q->subdev.entity, CIO2_PAD_SINK, > > - 0); > > - if (ret) { > > - dev_err(dev, "failed to create link for %s\n", > > - q->sensor->name); > > - return ret; > > - } > > - } > > - > > - return v4l2_device_register_subdev_nodes(&cio2->v4l2_dev); > > -} > > - > > static const struct v4l2_async_notifier_operations cio2_async_ops = { > > .bound = cio2_notifier_bound, > > .unbind = cio2_notifier_unbind, > > - .complete = cio2_notifier_complete, > > }; > > > > static int cio2_parse_firmware(struct cio2_device *cio2)
