Philips TouCam #4174
Comments
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In each case please post full logs. At a minimum, |
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Here's the lsusb -v entry for the camera: And the tail of dmesg: |
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And what is the output of dmesg once you have attempted to use the camera (and seen it fail)? |
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Here: |
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The pwc driver appears to do dma mapping itself in pwc_alloc_urb_buffer(), rather than using the USB HCD's automatic handling of mapping/unmapping on URB submission/hand-back or using usb_alloc_coherent()/usb_free_coherent(). It's also unique in doing it this way. |
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Hi P33M |
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I would suggest that the webcam belongs in a museum... The driver breakage is a regression, possibly due to internal API changes. It would need bisecting to find the exact commit between 5.4 and 5.10 that broke the driver. Bisecting upstream regressions is a bit of a pain on a Pi, since there are many downstream patches. It's usually faster to reproduce the bug on x86, then test the unmodified upstream kernel that way. My inclination would be to make the pwc driver do whatever the large pile of other webcam drivers do, but without hardware to test it on, chances of fixing it are small. |
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If you can reproduce the issue on x86 then it'd be worth reporting it upstream via the linux-media mailing list (http://vger.kernel.org/vger-lists.html#linux-media). |
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Thanks P33M - unfortunately you speak a different language from me as a mere engineer ;-) |
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Forum thread (now locked) - https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=305091 |
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If reproducible on 5.10 x86 (e.g Ubuntu Linux 21.04) and you want to pin down the exact version yourself, then there's a pretty comprehensive guide - might want to skip to "bisecting upstream kernels" though. If installing a dozen or so different kernels is daunting then I'd do what @6by9 suggests - report it upstream. |
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As if by magic: Already reported last month. Presumably patch will make its way through in due course. |
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Checking on patchwork.linuxtv.org, https://patchwork.linuxtv.org/project/linux-media/patch/[email protected]/ has been accepted. The patch you linked to has been marked as obsoleted (https://patchwork.linuxtv.org/project/linux-media/patch/[email protected]/). Although comment 8 is a little amusing considering this discussion. That fix will be in 5.12. |
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Hi all Thanks for finding the patch. Re comment 8 - yes indeed, there are people out here using non-intel devices. I have a collection of USB webcams which are slowly going 'stale'. When you say the fix will be in 5.12, is there a patch for armhf now, or do I build the driver from source, or something similar - sorry that I know so little about these matters as a retired space scientist/engineer ! Tony |
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I just looked at the link to bisecting upstream kernels - sorry - completely over my head! I'll wait for you experts to propagate the patch to us lesser mortals. |
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It has made it to Linus' master branch, and has a Fixes: tag, so it should make it's way back to the older stable kernels in due course (probably the next 2 weeks). Unless it is a critical patch then we don't expedite pulling the patch back to our trees. |
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Great there will be a fix. Maybe an old webcam but still very useful, and was very popular for astrophotography . |
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I reported this earlier in the Month see Hexxeh/rpi-firmware#254 |
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Hi FlareP1
Thanks for the heads up. I can also confirm that my PCVC740K ToUcam Pro is
now working. It's a useful webcam to use with the RPi400 which no longer
has the RPi camera connector. It also has a microphone in the camera - good
for Zoom meetings I hope.
Tony
…On Wed, 10 Mar 2021 at 17:50, FlareP1 ***@***.***> wrote:
I reported this earlier in the Month see Hexxeh/rpi-firmware#254
<Hexxeh/rpi-firmware#254>
Just tried the latest pre-release branch today which has been updated to
5.10.20-v7+and can confirm that the PWC webcam is now working again. In
order to get this you would need to follow the instuction here
https://www.raspberrypi.org/documentation/raspbian/applications/rpi-update.md
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Closing as fixed upstream. |
Latest linux version on Raspberry Pi 400, running VLC and other players, this USB webcam fails:
libv4l2: error turning on stream: cannot allocate memory
The camera is detected in lsusb:
Bus 001 Device 005: ID 0471:0311 Philips (or NXP) PCVC740K ToUcam Pro [pwc]
Version:
Linux raspberrypi 5.10.11-v7l+ #1399 SMP Thu Jan 28 12:09:48 GMT 2021 armv7l GNU/Linux
Also fails if you try to use pygame cam.start, can't allocate memory.
Previous version was OK:
Linux raspberrypi 5.4.79-v7l+ #1373 SMP Mon Nov 23 13:27:40 GMT 2020 armv7l GNU/Linux
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