On Thu, 19 Dec 2024 at 17:05, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > Hi, > > On 19-Dec-24 4:53 PM, Ricardo Ribalda wrote: > > On Thu, 19 Dec 2024 at 16:41, Laurent Pinchart > > <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > >> > >> On Thu, Dec 19, 2024 at 04:35:37PM +0100, Ricardo Ribalda wrote: > >>> On Thu, 19 Dec 2024 at 15:41, Laurent Pinchart wrote: > >>>> On Thu, Dec 19, 2024 at 09:17:31AM +0100, Ricardo Ribalda wrote: > >>>>> On Thu, 19 Dec 2024 at 00:27, Laurent Pinchart wrote: > >>>>>> On Fri, Dec 13, 2024 at 11:21:02AM +0000, Ricardo Ribalda wrote: > >>>>>>> To implement VIDIOC_QUERYCTRL, we need to read from the hardware all the > >>>>>>> values that were not cached previously. If that read fails, we used to > >>>>>>> report back the error to the user. > >>>>>>> > >>>>>>> Unfortunately this does not play nice with userspace. When they are > >>>>>>> enumerating the contols, the only expect an error when there are no > >>>>>>> "next" control. > >>>>>>> > >>>>>>> This is probably a corner case, and could be handled in userspace, but > >>>>>>> both v4l2-ctl and yavta fail to enumerate all the controls if we return > >>>>>>> then -EIO during VIDIOC_QUERYCTRL. I suspect that there are tons of > >>>>>>> userspace apps handling this wrongly as well. > >>>>>>> > >>>>>>> This patch get around this issue by ignoring the hardware errors and > >>>>>>> always returning 0 if a control exists. > >>>>>>> > >>>>>>> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> > >>>>>>> --- > >>>>>>> Hi 2*Hans and Laurent! > >>>>>>> > >>>>>>> I came around a device that was listing just a couple of controls when > >>>>>>> it should be listing much more. > >>>>>>> > >>>>>>> Some debugging latter I found that the device was returning -EIO when > >>>>>>> all the focal controls were read. > >>>>>> > >>>>>> Was it transient and random errors, or does the device always fail for > >>>>>> those controls ? > >>>>> > >>>>> For one of the devices the control is always failing (or I could not > >>>>> find a combination that made it work). > >>>>> > >>>>> For the other it was more or less random. > >>>> > >>>> Are there other controls that failed for that device ? And what > >>>> request(s) fail, is it only GET_CUR or also GET_MIN/GET_MAX/GET_RES ? > >>> > >>> It is a mix. > >>> > >>>> What's the approximate frequency of those random failures ? > >>>> > >>>>>>> This could be solved in userspace.. but I suspect that a lot of people > >>>>>>> has copied the implementation of v4l-utils or yavta. > >>>>>>> > >>>>>>> What do you think of this workaround? > >>>>>> > >>>>>> Pretending that the control could be queried is problematic. We'll > >>>>>> return invalid values to the user, I don't think that's a good idea. If > >>>>>> the problematic device always returns error for focus controls, we could > >>>>>> add a quirk, and extend the uvc_device_info structure to list the > >>>>>> controls to ignore. > >>>>>> > >>>>>> Another option would be to skip over controls that return -EIO within > >>>>>> the kernel, and mark those controls are broken. I think this could be > >>>>>> done transparently for userspace, the first time we try to populate the > >>>>>> cache for such controls, a -EIO error would mark the control as broken, > >>>>>> and from a userspace point of view it wouldn't be visible through as > >>>>>> ioctl. > >>>>> > >>>>> I see a couple of issues with this: > >>>>> - There are controls that fail randomly. > >>>>> - There are controls that fail based on the value of other controls > >>>>> (yeah, I know). > >>>> > >>>> I was fearing there would be random (or random-looking) failures, as > >>>> that can preclude marking the controls as broken and fully hiding them > >>>> from userspace :-( > >>>> > >>>>> - There are controls that do not implement RES, MIN, or MAX, but > >>>>> besides that, they are completely functional. > >>>>> In any of those cases we do not want to skip those controls. > >>>>> > >>>>> I am not against quirking specific cameras once we detect that they > >>>>> are broken... > >>>> > >>>> Hopefully there won't be too many of those, right ? Righhhht... ? > >>> > >>> So far I have identified 4 in a week, and I am not testing obscure > >>> camera modules.... > >> > >> Can you provide more information about those modules ? USB descriptors > >> maybe, and the list of controls that fail, and how they fail ? > > > > These are the ones I can share now: > > > > "13d3:5519": Focus value out of range > > focus_absolute 0x009a090a (int) : min=355 max=790 step=1 default=6 > > value=500 flags=inactive > > Hmm this one looks like min and default are swapped ? > > So I guess this one needs a quirk which checks if default < min > and in that case swaps them (the check is to avoid swapping > with fixed fw). If these are built into chromebooks how about > doing a fwupdate for the camera instead ? We do fwupdate whenever possible. But some modules are not updateable. They either: lack DFU, or the flash is read-only, or the update process has a non acceptable fail rate. We aim to detect compliance errors early in the development process. V4L2-compliance now (almost) works with the uvcvideo driver. And that helps a lot :) I plan to add quirks for the cameras that I can test. But we still need a solution for all the external cameras and modules that are not in the lab. > > > "3277:0003": Focus returns -EIO > > Focus Absolute and Focus, Automatic Continuous: return -EIO for at > > least one of get_ max/min/res > > > > "0408:302f": Error reading AutoExposure Flags > > UVC_GET_INFO returns invalid flags > > Regards, > > Hans > > > -- Ricardo Ribalda
