Hello everyone,

It looks like the current kernel driver for Hauppauge WinTV-HVR-5525 card supports all the digital inputs but seems to be missing analog A/V inputs.
In the past couple of months there was improvement on this driver where analog audio routing and some analog video was added for the WinTV-HVR-5525.
The analog video is detected on this card and registered device video* but the video signal cannot be captured due to missing analog a/v mux for .porta in the driver.
It is very likely that these missing multiplexers will be included in the driver soon.
In the meantime if you want to enable/add the analog inputs on this card try the following (tested on Slackware with Kernel 5.10.X but should work on any Linux):

cp -r /usr/src/linux-$(uname -r) /tmp/
wget axes2solution.com/hvr5525/files/cx23885.patch
patch -d/tmp/linux-$(uname -r) -p0 < cx23885.patch
cd /tmp/linux-$(uname -r)
make -C . M=drivers/media/pci/cx23885
mv /lib/modules/$(uname -r)/kernel/drivers/media/pci/cx23885/cx23885.ko /lib/modules/$(uname -r)/kernel/drivers/media/pci/cx23885/cx23885.ko.old
cp /tmp/linux-$(uname -r)/drivers/media/pci/cx23885/cx23885.ko /lib/modules/$(uname -r)/kernel/drivers/media/pci/cx23885/
depmod -a
reboot

You should be able to test the analog A/V with the following command:
mplayer -vf pp=lb -v tv:// -tv driver=v4l2:immediatemode=0:adevice=hw.2:alsa

where audio device hw.2 is taken from "arecord -l" (card 2: CX23885 [Conexant CX23885],.......)

Since I do not have any S-Video source I was only able to test the composite video input.

Thanks for posting