Re: [PATCH 23/24] drm/bridge: require the .owner to be filled in on drm_bridge_attach

Daniel Vetter
2018-04-30T15:24:46Z

On Fri, Apr 27, 2018 at 12:31:38AM +0200, Peter Rosin wrote:
> The .owner will be handy to have around.
>
> Signed-off-by: Peter Rosin <peda@axentia.se>
> ---
> drivers/gpu/drm/drm_bridge.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 9f023bd84d56..a038da696802 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -115,6 +115,9 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
> if (!encoder || !bridge)
> return -EINVAL;
>
> + if (WARN_ON(!bridge->owner))
> + return -EINVAL;

I think conceptually this is checked at the wrong place, and I think also misnamed
a bit. The ->owner is essentially the struct device (and its associated
driver) that provides the drm_bridge. As such it should be filled out
already at drm_bridge_add() time, and I think the check should be in
there. For driver-internal bridges it might make sense to also check this
here, not sure. Or just require all bridges get added.

Wrt the name, I think we should call this pdev or something. ->owner
usually means the module owner. I think in other subsystems ->dev is used,
but in drm we use ->dev for the drm_device pointer, so totally different
thing. pdev = physical device is the best I came up with. Better
suggestions very much welcome.
-Daniel

> +
> if (previous && (!previous->dev || previous->encoder != encoder))
> return -EINVAL;
>
> --
> 2.11.0
>
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--
Daniel Vetter
Software Engineer, Intel Corporation