Hi!,
On Wed, Jul 11, 2018 at 2:41 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> HI,
>
>
> On 11-07-18 14:08, Laurent Pinchart wrote:
>>
>> Hi Carlos,
>>
>> On Wednesday, 11 July 2018 14:36:48 EEST Carlos Garnacho wrote:
>>>
>>> On Wed, Jul 11, 2018 at 1:00 PM, Laurent Pinchart wrote:
>>>>
>>>> On Wednesday, 11 July 2018 11:37:14 EEST Hans de Goede wrote:
>>>>>
>>>>> Hi Laurent,
>>>>>
>>>>> At Guadec Carlos (in the Cc) told me that on his Acer 2-in-1 only
>>>>> the frontcam is working and it seems both are represented by a
>>>>> single UVC USB device. I've told him to check for some v4l control
>>>>> to flip between front and back.
>>>>>
>>>>> Carlos, as I mentioned you can try gtk-v4l
>>>>> ("sudo dnf install gtk-v4l") or qv4l2
>>>>> ("sudo dnf install qv4l2") these will both show
>>>>> you various controls for the camera. One of those might do the trick.
>>>>>
>>>>> But I recently bought a 2nd second hand Cherry Trail based HP
>>>>> X2 2-in-1 and much to my surprise that is actually using an UVC
>>>>> cam, rather then the usual ATOMISP crap and it has the same issue.
>>>>>
>>>>> This device does not seem to have a control to flip between the
>>>>> 2 cams, instead it registers 2 /dev/video? nodes but the second
>>>>> node does not work
>>>>
>>>>
>>>> The second node is there to expose metadata to userspace, not image
>>>> data.
>>>> That's a recent addition to the uvcvideo driver.
>>>>
>>>>> and dmesg contains:
>>>>>
>>>>> [ 26.079868] uvcvideo: Found UVC 1.00 device HP TrueVision HD
>>>>> (05c8:03a3)
>>>>> [ 26.095485] uvcvideo 1-4.2:1.0: Entity type for entity Extension 4
>>>>> was
>>>>> not initialized!
>>>>> [ 26.095492] uvcvideo 1-4.2:1.0: Entity type for entity Processing 2
>>>>> was
>>>>> not initialized!
>>>>> [ 26.095496] uvcvideo 1-4.2:1.0: Entity type for entity Camera 1 was
>>>>> not
>>>>> initialized!
>>>>
>>>>
>>>> You can safely ignore those messages. I need to submit a patch to get
>>>> rid
>>>> of them.
>>>>
>>>>> Laurent, I've attached lsusb -v output so that you can check the
>>>>> descriptors.
>>>>
>>>>
>>>> Thank you.
>>>>
>>>> It's funny how UVC specifies a standard way to describe a device with
>>>> two
>>>> camera sensors with dynamic selection of one of them at runtime, and
>>>> vendors instead implement vendor-specific crap :-(
>>>>
>>>> The interesting part in the descriptors is
>>>>
>>>> VideoControl Interface Descriptor:
>>>> bLength 27
>>>> bDescriptorType 36
>>>> bDescriptorSubtype 6 (EXTENSION_UNIT)
>>>> bUnitID 4
>>>> guidExtensionCode
>>>> {1229a78c-47b4-4094-b0ce-db07386fb938}
>>>> bNumControl 2
>>>> bNrPins 1
>>>> baSourceID( 0) 2
>>>> bControlSize 2
>>>> bmControls( 0) 0x00
>>>> bmControls( 1) 0x06
>>>> iExtension 0
>>>>
>>>> The extension unit exposes two controls (bmControls is a bitmask). They
>>>> can be accessed from userspace through the UVCIOC_CTRL_QUERY ioctl, or
>>>> mapped to V4L2 controls through the UVCIOC_CTRL_MAP ioctl, in which case
>>>> they will be exposed to standard V4L2 applications.
>>>>
>>>> If you want to experiment with this, I would advise querying both
>>>> controls
>>>> with UVCIOC_CTRL_QUERY. You can use the UVC_GET_CUR, UVC_GET_MIN,
>>>> UVC_GET_MAX, UVC_GET_DEF and UVC_GET_RES requests to get the control
>>>> current, minimum, maximum, default and resolution values, and
>>>> UVC_GET_LEN
>>>> and UVC_GET_INFO to get the control size (in bytes) and flags. Based on
>>>> that you can start experimenting with UVC_SET_CUR to set semi-random
>>>> values.
>>>>
>>>> I'm however worried that those two controls would be a register address
>>>> and a register value, for indirect access to all hardware registers in
>>>> the device. In that case, you would likely need information from the
>>>> device vendor, or possibly a USB traffic dump from a Windows machine
>>>> when
>>>> switching between the front and back cameras.
>>>>
>>>>> Carlos, it might be good to get Laurent your descriptors too, to do
>>>>> this do "lsusb", note what is the <vid>:<pid> for your camera and then
>>>>> run:
>>>>>
>>>>> sudo lsusb -v -d <vid>:<pid> > lsusb.log
>>>>>
>>>>> And send Laurent a mail with the generated lsusb
>>>>
>>>>
>>>> That would be appreciated, but I expect the same issue :-(
>>>
>>>
>>> Please find it attached. IIUC your last email, it might not be the
>>> exact same issue, but you can definitely judge better.
>>
>>
>> Your device is similar in the sense that it doesn't use the standard UVC
>> support for multiple camera sensors. It instead exposes two extension
>> units:
>>
>> VideoControl Interface Descriptor:
>> bLength 27
>> bDescriptorType 36
>> bDescriptorSubtype 6 (EXTENSION_UNIT)
>> bUnitID 4
>> guidExtensionCode {1229a78c-47b4-4094-b0ce-db07386fb938}
>> bNumControl 2
>> bNrPins 1
>> baSourceID( 0) 2
>> bControlSize 2
>> bmControls( 0) 0x00
>> bmControls( 1) 0x06
>> iExtension 0
>> VideoControl Interface Descriptor:
>> bLength 29
>> bDescriptorType 36
>> bDescriptorSubtype 6 (EXTENSION_UNIT)
>> bUnitID 6
>> guidExtensionCode {26b8105a-0713-4870-979d-da79444bb68e}
>> bNumControl 9
>> bNrPins 1
>> baSourceID( 0) 4
>> bControlSize 4
>> bmControls( 0) 0x1f
>> bmControls( 1) 0x01
>> bmControls( 2) 0x38
>> bmControls( 3) 0x00
>> iExtension 6 Realtek Extended Controls Unit
>>
>> The first one is identical to Hans', and I expect it to offer indirect
>> access
>> to internal device registers. The second one exposes 9 controls, and I
>> expect
>> at least some of those to have direct effects on the device. What they do
>> and
>> how they operate is unfortunately unknown.
>
>
> Laurent, thank you for your input on this. I thought it was a bit weird that
> the cam on my HP X2 only had what appears to be the debug controls, so I
> opened it up and as I suspect (after your analysis) it is using a USB module
> for the front camera, but the back camera is a sensor directly hooked with
> its
> CSI/MIPI bus to the PCB, so very likely it is using the ATOMISP stuff.
>
> So I think that we can consider this "solved" for my 2-in-1.
>
> Carlos, your Acer is using a Core CPU (not an Atom) right ? And the front
Indeed, it is an i5...
> and
> rear cams are both centered at the same edge I guess ? (mine had one in the
> corner and the other centered which already was a hint)
...but now that you mention this, I have front camera centered and
rear camera on a corner too. Is there any other info I may need to
fetch? I assume ATOMISP is irrelevant here.
Cheers,
Carlos
