How to select VIDEOBUF2_DMA_SG in kernel config?

[simonvanderveldt]

Thanks for the ebuild for the macbook webcam!
When emerging it I ran into the issue that my current kernel doesn't have CONFIG_VIDEOBUF2_DMA_SG enabled. I was wondering how you enabled it because apparently it's not possible to toggle it directly through make menuconfig, it's only toggled as a dependency for all kinds of other drivers which I don't really want to install.
Of course manually adding it to the kernel config doesn't really work since it'll be removed when running make menuconfig.

[toaster]

Hi Simon,

sadly I have no Gentoo Desktop anymore since my employer switched to the new MBP with touch bar. I can't remember which driver I had installed to get CONFIG_VIDEOBUF2_DMA_SG. Maybe it was some V4L stuff.

Sorry, that I could not help you here.

[simonvanderveldt]

Np, thanks for the quick response!
Seems like the only way is to enable some piece of hardware in the kernel that enables VIDEOBUF2_DMA_SG. I looked in the gentoo tree and that's also what for example ndiswrapper does https://github.com/gentoo/gentoo/blob/master/net-wireless/ndiswrapper/ndiswrapper-1.61.ebuild#L33

I've gone for CONFIG_VIDEO_TW68 which relies on the smallest amount of dependencies and only enables VIDEOBUF2_DMA_SG, not other settings. See https://github.com/torvalds/linux/blob/5924bbecd0267d87c24110cbe2041b5075173a25/drivers/media/pci/tw68/Kconfig#L4

Maybe a similar hint that one could/should enable this like ndiswrapper does would be helpful?