On 06/04/2017 03:41 PM, Alexandre Macabies wrote: > Hello, I forgot to Cc: the full list of maintainers for this patch. This follow-up includes them. Sorry for the noise! My original email & patch is quoted below. Best, Alexandre > This thread comes after two others[1][2] about a similar issue. > > I own a USB video microscope[3] from Dino-Lite. Even if the constructor does > not advertise it as being supported on Linux, it is mostly a "good citizen" > camera: it registers as a standard USB video device and as such, it is properly > recognized by uvcvideo. > > This device is equipped with an integrated illuminator/lamp -- a set of LEDs. > After some research (using a USB sniffer) I managed to identify the > non-standard XU control used to switch this lamp on and off: one shall send > either 80 01 f0 (off) or 80 01 f1 (on) to XU control unit 4 selector 3. > > So at first I tried to send a raw ctrl_set using: > > $ uvcdynctrl -S 4:3 8001f0 > [...] > query control size of : 1 > [...] > ERROR: Unable to set the control value: Invalid argument. (Code: 3) > > Indeed, the device reports this XU as being only 1 in length, but the payload > has to be 3 bytes. So I assume there is a bug (or deliberate inaccuracy) in the > GET_LEN reply from the device firmware. To overcome this issue, I compiled > a patched version of uvcvideo in which uvc_query_ctrl[4] returns an hardcoded > size of 3 for this specific device & UX control. I was finally able to switch > the lamp on and off: > > $ uvcdynctrl -S 4:3 8001f0 > [39252.854261] uvcvideo: Fixing USB a168:0870 UX control 4/3 len: 1 -> 3 > [...] > query control size of : 3 > [...] > set value of : (LE)0x8001f0 (BE)0xf00180 > [lamp goes off] > > You can find the patch below. I abstracted it in the spirit of > uvc_ctrl_fixup_xu_info[5] so we can add more entries to the table in the > future. What do you think, would it be relevant to merge? AFAICT there is no > API in uvcvideo or v4l for controlling this kind of illuminator/lamp features, > so giving userland the ability to control the devices via XU by lying seems to > be the only solution. > > Best, > > Alexandre > > [1] "Dino-Lite uvc support", 2008, https://sourceforge.net/p/linux-uvc/mailman/message/29831153/ > [2] "switching light on device Dino-Lite Premier", 2013, https://sourceforge.net/p/linux-uvc/mailman/message/31219122/ > [3] https://www.dinolite.us/products/digital-microscopes/usb/basic/am4111t > [4] http://elixir.free-electrons.com/linux/v4.11/source/drivers/media/usb/uvc/uvc_video.c#L72 > [5] http://elixir.free-electrons.com/linux/v4.11/source/drivers/media/usb/uvc/uvc_ctrl.c#L1593 > > Signed-off-by: Alexandre Macabies <web+oss@xxxxxxxxxxx> > > --- > drivers/media/usb/uvc/uvc_video.c | 37 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 37 insertions(+) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index 07a6c833ef7b..839dc02b4f33 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -69,6 +69,40 @@ static const char *uvc_query_name(__u8 query) > } > } > > +static void uvc_fixup_query_ctrl_len(const struct uvc_device *dev, __u8 unit, > + __u8 cs, void *data) > +{ > + struct uvc_ctrl_fixup { > + struct usb_device_id id; > + u8 unit; > + u8 selector; > + u16 len; > + }; > + > + static const struct uvc_ctrl_fixup fixups[] = { > + // Dino-Lite Premier (AM4111T) > + { { USB_DEVICE(0xa168, 0x0870) }, 4, 3, 3 }, > + }; > + > + unsigned int i; > + > + for (i = 0; i < ARRAY_SIZE(fixups); ++i) { > + if (!usb_match_one_id(dev->intf, &fixups[i].id)) > + continue; > + > + if (!(fixups[i].unit == unit && fixups[i].selector == cs)) > + continue; > + > + uvc_trace(UVC_TRACE_CONTROL, > + "Fixing USB %04x:%04x %u/%u GET_LEN: %u -> %u", > + fixups[i].id.idVendor, fixups[i].id.idProduct, > + unit, cs, > + le16_to_cpup((__le16 *)data), fixups[i].len); > + *((__le16 *)data) = cpu_to_le16(fixups[i].len); > + break; > + } > +} > + > int uvc_query_ctrl(struct uvc_device *dev, __u8 query, __u8 unit, > __u8 intfnum, __u8 cs, void *data, __u16 size) > { > @@ -83,6 +117,9 @@ int uvc_query_ctrl(struct uvc_device *dev, __u8 query, __u8 unit, > return -EIO; > } > > + if (query == UVC_GET_LEN && size == 2) > + uvc_fixup_query_ctrl_len(dev, unit, cs, data); > + > return 0; > } > > > -- > 2.13.0 >
