Re: [PATCH] staging: media: tegra-video: vi: fix probe failure on skipped last port

[Luca Ceresoli]

Hello,

On Tue Jul 7, 2026 at 5:24 PM CEST, Hao-Qun Huang wrote:
> tegra_vi_channels_alloc() iterates over port nodes and skips those
> whose reg property cannot be read or whose remote endpoint fails
> v4l2_fwnode_endpoint_parse(), leaving the negative result of the
> failed call in ret. If that happens on the last port node, the loop
> ends with ret still negative and tegra_vi_init() fails the whole VI
> probe.
>
> The same defective port earlier in the ports node is skipped silently,
> so probing succeeds or fails depending on the order of the port nodes.
> The CSI equivalent, tegra_csi_channels_alloc(), returns 0
> unconditionally after its loop and does not have this problem.
>
> Use a separate variable for the per-port checks so that only fatal
> errors end up in ret.
>
> Fixes: 1ebaeb09830f ("media: tegra-video: Add support for external sensor capture")
> Fixes: 2ac4035a78c9 ("media: tegra-video: Add support for x8 captures with gang ports")
> Assisted-by: Claude:claude-fable-5
> Signed-off-by: Hao-Qun Huang <alvinhuang0603@xxxxxxxxx>

Do you have a real use case where ths failure happens?

Also, mixing two different return values may solve a bug but makes for more
intricated. I'd rather second a fix based on moving the whole foreach loop
body into a subfunction, and make the foreach loop body as simple as
calling the subfunction and handling returned errors. This would fix the
code making it more readbale.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com