On Thu, Aug 25, 2016 at 11:04:32AM +0200, Andrea Merello wrote:
> Up to now, once a bridge has been attached to a DRM device, it cannot
> be undone.
>
> In particular you couldn't rmmod/insmod a DRM driver that uses a bridge,
> because the bridge would remain bound to the first (dead) driver instance.
>
> This patch fixes this by introducing drm_encoder_detach() and a ->detach
> callback in drm_bridge_funcs for the bridge to be notified about detaches.
>
> It's DRM/KMS driver responsibility to call drm_encoder_detach().
>
> While adding the bridge detach callback, with its kerneldoc, I also added
> kerneldoc for attach callback.
>
> Few other kerneldocs fixes around there are included.
>
> Suggested-by: Daniel Vetter <daniel@xxxxxxxx>
> Suggested-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx>
> Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
As discussed on the last round, I'll let Archit apply all 3 to drm-misc,
so he can check them out too.
-Daniel
> ---
> drivers/gpu/drm/drm_bridge.c | 29 +++++++++++++++++++++++++++--
> include/drm/drm_crtc.h | 26 +++++++++++++++++++++++++-
> 2 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index 2555430..4840466 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -98,11 +98,11 @@ EXPORT_SYMBOL(drm_bridge_remove);
> * @dev: DRM device
> * @bridge: bridge control structure
> *
> - * called by a kms driver to link one of our encoder/bridge to the given
> + * Called by a kms driver to link one of our encoder/bridge to the given
> * bridge.
> *
> * Note that setting up links between the bridge and our encoder/bridge
> - * objects needs to be handled by the kms driver itself
> + * objects needs to be handled by the kms driver itself.
> *
> * RETURNS:
> * Zero on success, error code on failure
> @@ -125,6 +125,31 @@ int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
> EXPORT_SYMBOL(drm_bridge_attach);
>
> /**
> + * drm_bridge_detach - deassociate given bridge from its DRM device
> + *
> + * @bridge: bridge control structure
> + *
> + * Called by a kms driver to unlink the given bridge from its DRM device.
> + *
> + * Note that tearing down links between the bridge and our encoder/bridge
> + * objects needs to be handled by the kms driver itself.
> + */
> +void drm_bridge_detach(struct drm_bridge *bridge)
> +{
> + if (WARN_ON(!bridge))
> + return;
> +
> + if (WARN_ON(!bridge->dev))
> + return;
> +
> + if (bridge->funcs->detach)
> + bridge->funcs->detach(bridge);
> +
> + bridge->dev = NULL;
> +}
> +EXPORT_SYMBOL(drm_bridge_detach);
> +
> +/**
> * DOC: bridge callbacks
> *
> * The &drm_bridge_funcs ops are populated by the bridge driver. The DRM
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 3fa0275..bb214a1 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -1118,12 +1118,33 @@ struct drm_plane {
>
> /**
> * struct drm_bridge_funcs - drm_bridge control functions
> - * @attach: Called during drm_bridge_attach
> */
> struct drm_bridge_funcs {
> + /**
> + * @attach:
> + *
> + * This callback is invoked whenever our bridge is being attached to a
> + * &drm_encoder.
> + *
> + * The attach callback is optional.
> + *
> + * RETURNS:
> + *
> + * Zero on success, error code on failure.
> + */
> int (*attach)(struct drm_bridge *bridge);
>
> /**
> + * @detach:
> + *
> + * This callback is invoked whenever our bridge is being detached from a
> + * &drm_encoder.
> + *
> + * The detach callback is optional.
> + */
> + void (*detach)(struct drm_bridge *bridge);
> +
> + /**
> * @mode_fixup:
> *
> * This callback is used to validate and adjust a mode. The paramater
> @@ -1137,6 +1158,8 @@ struct drm_bridge_funcs {
> * this function passes all other callbacks must succeed for this
> * configuration.
> *
> + * The mode_fixup callback is optional.
> + *
> * NOTE:
> *
> * This function is called in the check phase of atomic modesets, which
> @@ -2426,6 +2449,7 @@ extern int drm_bridge_add(struct drm_bridge *bridge);
> extern void drm_bridge_remove(struct drm_bridge *bridge);
> extern struct drm_bridge *of_drm_find_bridge(struct device_node *np);
> extern int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge);
> +extern void drm_bridge_detach(struct drm_bridge *bridge);
>
> bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
> const struct drm_display_mode *mode,
> --
> 2.7.4
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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