lkml.org 
[lkml]   [2019]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 01/30] drm: Introduce drm_bridge_init()
On Tue, Nov 26, 2019 at 4:55 PM Mihail Atanassov
<Mihail.Atanassov@arm.com> wrote:
>
> Hi Daniel,
>
> Thanks for the quick review.
>
> On Tuesday, 26 November 2019 14:26:10 GMT Daniel Vetter wrote:
> > On Tue, Nov 26, 2019 at 01:15:59PM +0000, Mihail Atanassov wrote:
> > > A simple convenience function to initialize the struct drm_bridge.
> > >
> > > Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
> >
> > The commit message here leaves figuring out why we need this to the
> > reader. Reading ahead the reasons seems to be to roll out bridge->dev
> > setting for everyone, so that we can set the device_link. Please explain
> > that in the commit message so the patch is properly motivated.
>
> Ack, but with one caveat: bridge->dev is the struct drm_device that is
> the bridge client, we need to add a bridge->device (patch 29 in this
> series) which is the struct device that will manage the bridge lifetime.

Ah yes, ->dev is for drm_bridge_attach.

> >
> > > ---
> > > drivers/gpu/drm/drm_bridge.c | 29 +++++++++++++++++++++++++++++
> > > include/drm/drm_bridge.h | 4 ++++
> > > 2 files changed, 33 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> > > index cba537c99e43..cbe680aa6eac 100644
> > > --- a/drivers/gpu/drm/drm_bridge.c
> > > +++ b/drivers/gpu/drm/drm_bridge.c
> > > @@ -89,6 +89,35 @@ void drm_bridge_remove(struct drm_bridge *bridge)
> > > }
> > > EXPORT_SYMBOL(drm_bridge_remove);
> > >
> > > +/**
> > > + * drm_bridge_init - initialise a drm_bridge structure
> > > + *
> > > + * @bridge: bridge control structure
> > > + * @funcs: control functions
> > > + * @dev: device
> > > + * @timings: timing specification for the bridge; optional (may be NULL)
> > > + * @driver_private: pointer to the bridge driver internal context (may be NULL)
> >
> > Please also sprinkle some links to this new function to relevant places,
> > I'd add at least:
> >
> > "Drivers should call drm_bridge_init() first." to the kerneldoc for
> > drm_bridge_add. drm_bridge_add should also mention drm_bridge_remove as
> > the undo function.
> >
> > And perhaps a longer paragraph to &struct drm_bridge:
> >
> > "Bridge drivers should call drm_bridge_init() to initialized a bridge
> > driver, and then register it with drm_bridge_add().
> >
> > "Users of bridges link a bridge driver into their overall display output
> > pipeline by calling drm_bridge_attach()."
>
> Will do.
>
> >
> > > + */
> > > +void drm_bridge_init(struct drm_bridge *bridge, struct device *dev,
> > > + const struct drm_bridge_funcs *funcs,
> > > + const struct drm_bridge_timings *timings,
> > > + void *driver_private)
> > > +{
> > > + WARN_ON(!funcs);
> > > +
> > > + bridge->dev = NULL;
> >
> > Given that the goal here is to get bridge->dev set up, why not
> >
> > WARN_ON(!dev);
> > bridge->dev = dev;
>
> See above struct device vs struct drm_device. I add a
>
> bridge->device = dev;
>
> in patch 29, which takes care of that. I skipped the warn since
> there's a dereference of dev, but I now realized it's behind CONFIG_OF,
> so I'll add it in for v2.

Ok, sounds good. Having the WARN_ON in patch 1 should also help making
sure all the conversion patches dtrt (and any future users).
-Daniel

> Yes, 'device' isn't the best of names, but I took Russell's patch
> almost as-is, I didn't have any better ideas for bikeshedding.
>
> >
> > That should help us to really move forward with all this.
> > -Daniel
> >
> > > + bridge->encoder = NULL;
> > > + bridge->next = NULL;
> > > +
> > > +#ifdef CONFIG_OF
> > > + bridge->of_node = dev->of_node;
> > > +#endif
> > > + bridge->timings = timings;
> > > + bridge->funcs = funcs;
> > > + bridge->driver_private = driver_private;
> > > +}
> > > +EXPORT_SYMBOL(drm_bridge_init);
> > > +
> > > /**
> > > * drm_bridge_attach - attach the bridge to an encoder's chain
> > > *
> > > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> > > index c0a2286a81e9..d6d9d5301551 100644
> > > --- a/include/drm/drm_bridge.h
> > > +++ b/include/drm/drm_bridge.h
> > > @@ -402,6 +402,10 @@ struct drm_bridge {
> > >
> > > void drm_bridge_add(struct drm_bridge *bridge);
> > > void drm_bridge_remove(struct drm_bridge *bridge);
> > > +void drm_bridge_init(struct drm_bridge *bridge, struct device *dev,
> > > + const struct drm_bridge_funcs *funcs,
> > > + const struct drm_bridge_timings *timings,
> > > + void *driver_private);
> > > struct drm_bridge *of_drm_find_bridge(struct device_node *np);
> > > int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
> > > struct drm_bridge *previous);
> >
> >
>
>
> --
> Mihail
>
>
>


--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

\
 
 \ /
  Last update: 2019-11-26 18:04    [W:0.086 / U:3.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site