Hi Hans On Mon, 25 Oct 2021 at 12:10, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > > On 25/10/2021 13:03, Dave Stevenson wrote: > > Hi All. > > > > On Mon, 25 Oct 2021 at 11:47, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >> > >> On 25/10/2021 12:30, Laurent Pinchart wrote: > >>> Hi Hans, > >>> > >>> On Mon, Oct 25, 2021 at 12:06:30PM +0200, Hans de Goede wrote: > >>>> Hi All, > >>>> > >>>> With my (and Dan's) kernel patch-series to enable the back camera on > >>>> the Surface Go shaping up (and hopefully going upstream soon), > >>>> the next step is to enable control of the focus lens for the back > >>>> camera. > >>>> > >>>> The focus is controlled through a separate i2c-client which is > >>>> described by a 2nd I2cSerialBusV2 resource entry in the ACPI > >>>> device for the ov8865 sensor. By default the kernel only instantiates > >>>> an i2c-client for the first I2cSerialBusV2 resource entry for an > >>>> ACPI device, getting an i2c-client for the 2nd one is easy and > >>>> out of scope for this discussion. > >>>> > >>>> The question which I have is, assuming we have the 2nd i2c-client > >>>> instantiated and we have a i2c-driver binding to it, how do we > >>>> represent the focus control to userspace. > >>>> > >>>> I see 2 possible directions we can go here: > >>>> > >>>> 1. Somehow inject an extra v4l2ctrl for this into the v4l2ctrl > >>>> list of the sensor. AFAIK we don't have infra for this atm, but > >>>> we could add some generic mechanism to do this to the v4l2-ctrls > >>>> core. IMHO from a userspace pov this is the cleanest, but at the > >>>> cost of some extra work / possible ugliness on the kernel side. > >>>> > >>>> 2. Register a separate v4l2_subdev for the focus-ctrl and in > >>>> some way provide information to userspace to which sensor this > >>>> belongs. > >>> > >>> The second approach is what V4L2 does already. We have a set of drivers > >>> for VCMs already (search for V4L2_CID_FOCUS_ABSOLUTE in > >>> drivers/media/i2c/). > >>> > >>>> I believe that both are valid approaches. So before diving into > >>>> this I wonder what others are thinking about this. > >>>> > >>>> Specific questions: > >>>> > >>>> 1. Hans Verkuil, what do you think about adding > >>>> support for another driver to inject ctrls into the ctrl > >>>> list of another v4l2(sub)dev ? Maybe something like this > >>>> already exists ? If not do you think this is feasible > >>>> and desirable to add ? > >>>> > >>>> 2. If we go with a separate v4l2_subdev, how do we communicate > >>>> to which sensor the focus-control belongs to userspace ? > >>> > >>> The information was initially envisioned to be conveyed to userspace > >>> through the media controller API, using the entity group ID to group the > >>> camera sensor, lens controller and flash controller, but the > >>> media_entity_desc.group_id field is now obsolete. No other mechanism > >>> exist to replace that as far as I know, so we'll have to create > >>> something. There have been some talks about using a special kind of link > >>> to expose the relationship between the camera sensor and other > >>> components. > >>> > >> > >> I thought this was implemented: there should be an interface link from the > >> sensor entity to the subdev for the flash or focus control. > >> > >> To my knowledge, this is all available. > > > > We've been looking at focus and AF over the last few weeks, although > > under device tree instead of ACPI. > > > > With DT we have a lens driver bound to the sensor driver by giving the > > sensor a lens-focus = <&vcm>; entry. > > Media controller then reports it all under one entity, but it may be > > true that we don't have a linking between the lens subdev and sensor. > > > > pi@raspberrypi:~ $ media-ctl -p -d /dev/media2 > > Media controller API version 5.10.74 > > > > Media device information > > ------------------------ > > driver unicam > > model unicam > > serial > > bus info platform:fe801000.csi > > hw revision 0x0 > > driver version 5.10.74 > > > > Device topology > > - entity 1: imx477 10-001a (2 pads, 2 links) > > type V4L2 subdev subtype Sensor flags 0 > > device node name /dev/v4l-subdev0 > > pad0: Source > > [fmt:SRGGB12_1X12/4056x3040 field:none colorspace:unknown > > xfer:none ycbcr:601 quantization:full-range > > crop.bounds:(8,16)/4056x3040 > > crop:(8,16)/4056x3040] > > -> "unicam-image":0 [ENABLED,IMMUTABLE] > > pad1: Source > > [fmt:unknown/16384x1 field:none > > crop.bounds:(8,16)/4056x3040 > > crop:(8,16)/4056x3040] > > -> "unicam-embedded":0 [ENABLED,IMMUTABLE] > > > > - entity 4: ad5398 focus (0 pad, 0 link) > > type V4L2 subdev subtype Lens flags 0 > > device node name /dev/v4l-subdev1 > > > > - entity 5: unicam-image (1 pad, 1 link) > > type Node subtype V4L flags 1 > > device node name /dev/video0 > > pad0: Sink > > <- "imx477 10-001a":0 [ENABLED,IMMUTABLE] > > > > - entity 11: unicam-embedded (1 pad, 1 link) > > type Node subtype V4L flags 0 > > device node name /dev/video1 > > pad0: Sink > > <- "imx477 10-001a":1 [ENABLED,IMMUTABLE] > > > > The Pi may be slightly different from other platforms in that if you > > enable the second CSI2 interface then it'll be a totally separate > > /dev/media node, so we can view it as one overall entity even if not > > identified as such. > > > > The above was grabbed with an IMX477 with AF module. I haven't pushed > > that configuration anywhere, but IMX135 with lens driver is at > > https://github.com/raspberrypi/linux/pull/4612/ > > > > What is the output of: > > v4l2-compliance -M /dev/media2 --verbose > > That will also report any interface links. pi@raspberrypi:~/nfs/v4l-utils/utils/v4l2-compliance $ ./v4l2-compliance -M /dev/media2 --verbose v4l2-compliance 1.21.0-4859, 32 bits, 32-bit time_t v4l2-compliance SHA: 493af03f3c57 2021-10-08 17:23:11 Compliance test for unicam device /dev/media2: Media Driver Info: Driver name : unicam Model : unicam Serial : Bus info : platform:fe801000.csi Media version : 5.10.74 Hardware revision: 0x00000000 (0) Driver version : 5.10.74 Required ioctls: test MEDIA_IOC_DEVICE_INFO: OK test invalid ioctls: OK Allow for multiple opens: test second /dev/media2 open: OK test MEDIA_IOC_DEVICE_INFO: OK test for unlimited opens: OK Media Controller ioctls: Entity: 0x00000001 (Name: 'imx477 10-001a', Function: Camera Sensor) Entity: 0x00000004 (Name: 'ad5398 focus', Function: Lens Controller) Entity: 0x00000005 (Name: 'unicam-image', Function: V4L2 I/O, Flags: default) Entity: 0x0000000b (Name: 'unicam-embedded', Function: V4L2 I/O) Interface: 0x03000007 (Type: V4L Video, DevPath: /dev/video0) Interface: 0x0300000d (Type: V4L Video, DevPath: /dev/video1) Interface: 0x03000011 (Type: V4L Sub-Device, DevPath: /dev/v4l-subdev0) Interface: 0x03000013 (Type: V4L Sub-Device, DevPath: /dev/v4l-subdev1) Pad: 0x01000002 (0, imx477 10-001a, Source) Pad: 0x01000003 (1, imx477 10-001a, Source) Pad: 0x01000006 (0, unicam-image, Sink) Pad: 0x0100000c (0, unicam-embedded, Sink) Link: 0x02000008 (unicam-image to interface /dev/video0) Link: 0x02000009 (imx477 10-001a:0 -> unicam-image:0, Data, Enabled, Immutable) Link: 0x0200000e (unicam-embedded to interface /dev/video1) Link: 0x0200000f (imx477 10-001a:1 -> unicam-embedded:0, Data, Enabled, Immutable) Link: 0x02000012 (imx477 10-001a to interface /dev/v4l-subdev0) Link: 0x02000014 (ad5398 focus to interface /dev/v4l-subdev1) test MEDIA_IOC_G_TOPOLOGY: OK Entities: 4 Interfaces: 4 Pads: 4 Links: 6 Entity: 0x00000001 (Name: 'imx477 10-001a', Type: Camera Sensor, DevPath: /dev/v4l-subdev0) Entity: 0x00000004 (Name: 'ad5398 focus', Type: Lens Controller, DevPath: /dev/v4l-subdev1) Entity: 0x00000005 (Name: 'unicam-image', Type: V4L2 I/O, Flags: default, DevPath: /dev/video0) Entity: 0x0000000b (Name: 'unicam-embedded', Type: V4L2 I/O, DevPath: /dev/video1) test MEDIA_IOC_ENUM_ENTITIES/LINKS: OK test MEDIA_IOC_SETUP_LINK: OK Total for unicam device /dev/media2: 8, Succeeded: 8, Failed: 0, Warnings: 0 Dave
