Re: [PATCH 3/3] [media] uvcvideo: skip non-extension unit controls on Oculus Rift Sensors

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Philipp,

On Saturday 15 Jul 2017 15:13:45 Philipp Zabel wrote:
> Am Samstag, den 15.07.2017, 12:54 +0300 schrieb Laurent Pinchart:
> > On Friday 14 Jul 2017 22:14:24 Philipp Zabel wrote:
> >> The Oculus Rift Sensors (DK2 and CV1) allow to configure their sensor
> >> chips directly via I2C commands using extension unit controls. The
> >> processing and camera unit controls do not function at all.
> > 
> > Do the processing and camera units they report controls that don't work
> > when  exercised ? Who in a sane state of mind could have designed such a
> > terrible product ?
> 
> Yes. Without this patch I get a bunch of controls that have no effect
> whatsoever.
> 
> > If I understand you correctly, this device requires userspace code that
> > knows  how to program the sensor (and possibly other chips). If that's
> > the case, is there an open-source implementation of that code publicly
> > available ?
>
> Well, it's all still a bit in the experimentation phase. We have an
> implementation to set up the DK2 camera for synchronised exposure
> triggered by the Rift DK2 HMD and to read the calibration data from
> flash, here:
> 
> https://github.com/pH5/ouvrt/blob/master/src/esp570.c
> https://github.com/pH5/ouvrt/blob/master/src/mt9v034.c
> 
> And an even more rough version to set up the CV1 camera for
> synchronised exposure triggered by the Rift CV1 HMD here:
> 
> https://github.com/OpenHMD/OpenHMD-RiftPlayground/blob/master/src/main.c
> 
> The latter is using libusb, as it needs the variable length SPI data
> control.
> 
> Do you think adding a pseudo i2c driver for the eSP570/eSP770u webcam
> controllers and then exposing the sensor chips as V4L2 subdevices could
> be a good idea? We already have a sensor driver for the MT9V034 in the
> DK2 USB camera.

Yes, I think a device-specific driver would make sense, especially if we can 
implement support for the sensor as a standalone V4L2 subdev driver. The 
device only fakes UVC compatibility :-(

-- 
Regards,

Laurent Pinchart