[libcamera-devel] [PATCH 0/2] rkisp1: don't enable immutable link

[Laurent Pinchart]

Hi Helen,

(CC'ing Niklas)

On Wed, Feb 26, 2020 at 11:59:59PM -0300, Helen Koike wrote:
> The following patch was merged in the Linux kernel media tree:
> 3eed7385bff6 ("media: staging: media: rkisp1: make links immutable by default")
> 
> Which causes the topology configuration in libcamera to fail, since it tries to
> enable immutable links.
> 
> This patchset fixes the rkisp1-capture.sh scrips and the pipeline
> handler.
> 
> Question: I was wondering how releases are being mananged by libcamera.
> Does this patchset needs to wait for the patch mentioned above to reach
> mainline kernel?

Short answer: we don't have a release process yet :-) Longer term our
baseline for merging code in libcamera is having corresponding support
in mainline. For drivers not in staging, userspace API breakages are not
allowed, so we'd need to consider that for kernel changes. For drivers
in staging I think waiting for the change to appear in a release would
be nice for end-users.

I think we'll need to care about backward compatibility, and handle that
in libcamera. This may actually make it easier to change the kernel
userspace API in a non backward-compatible way. For this specific
change, enabling an immutable link should be a no-op, right ? We would
then likely keep the code in libcamera, maybe with a comment explaining
the issue, and with a scheduled removal data.

As we have no release yet, I think we can just merge the changes
already. Niklas, any opinion ? Can you handle this ?

> Helen Koike (2):
>   utils: rkisp1: don't enable immutable link
>   libcamera: pipeline: rkisp1: don't enable immutable link
> 
>  src/libcamera/pipeline/rkisp1/rkisp1.cpp | 8 --------
>  utils/rkisp1/rkisp1-capture.sh           | 1 -
>  2 files changed, 9 deletions(-)

-- 
Regards,

Laurent Pinchart