linux-kernel - Re: [PATCH v6 13/26] drm/encoder: add drm_encoder_cleanup

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Message-ID: <20250207095318.2fc8d54e@booty>
Date: Fri, 7 Feb 2025 09:53:18 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Simona Vetter <simona@...ll.ch>, Inki Dae <inki.dae@...sung.com>, Jagan
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 <paul.kocialkowski@...tlin.com>
Subject: Re: [PATCH v6 13/26] drm/encoder: add drm_encoder_cleanup_from()

On Fri, 7 Feb 2025 05:03:13 +0200
Dmitry Baryshkov <dmitry.baryshkov@...aro.org> wrote:

> On Thu, Feb 06, 2025 at 07:14:28PM +0100, Luca Ceresoli wrote:
> > Supporting hardware whose final part of the DRM pipeline can be physically
> > removed requires the ability to detach all bridges from a given point to
> > the end of the pipeline.
> > 
> > Introduce a variant of drm_encoder_cleanup() for this.
> > 
> > Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
> > 
> > ---
> > 
> > Changes in v6: none
> > Changes in v5: none
> > Changes in v4: none
> > Changes in v3: none
> > 
> > Changed in v2:
> >  - fix a typo in a comment
> > ---
> >  drivers/gpu/drm/drm_encoder.c | 21 +++++++++++++++++++++
> >  include/drm/drm_encoder.h     |  1 +
> >  2 files changed, 22 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> > index 8f2bc6a28482229fd0b030a1958f87753ad7885f..472dfbefe2960924a4e83bec425af8c7ef5f5265 100644
> > --- a/drivers/gpu/drm/drm_encoder.c
> > +++ b/drivers/gpu/drm/drm_encoder.c
> > @@ -207,6 +207,27 @@ void drm_encoder_cleanup(struct drm_encoder *encoder)
> >  }
> >  EXPORT_SYMBOL(drm_encoder_cleanup);
> >  
> > +/**
> > + * drm_encoder_cleanup_from - remove a given bridge and all the following
> > + * @encoder: encoder whole list of bridges shall be pruned
> > + * @bridge: first bridge to remove
> > + *
> > + * Removes from an encoder all the bridges starting with a given bridge
> > + * and until the end of the chain.
> > + *
> > + * This should not be used in "normal" DRM pipelines. It is only useful for
> > + * devices whose final part of the DRM chain can be physically removed and
> > + * later reconnected (possibly with different hardware).
> > + */
> > +void drm_encoder_cleanup_from(struct drm_encoder *encoder, struct drm_bridge *bridge)
> > +{
> > +	struct drm_bridge *next;
> > +
> > +	list_for_each_entry_safe_from(bridge, next, &encoder->bridge_chain, chain_node)
> > +		drm_bridge_detach(bridge);
> > +}
> > +EXPORT_SYMBOL(drm_encoder_cleanup_from);  
> 
> Shouldn't drm_encoder_cleanup() also use this function?

Sure. I'll do it in v7.

Luca

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