Re: [PATCH 1/4] drm: allow drm_atomic_print_state() to accept any drm_printer

[abhinavk@xxxxxxxxxxxxxx]

Hi Daniel

On 2020-10-22 03:38, Daniel Vetter wrote:
> On Wed, Oct 21, 2020 at 10:01:45PM -0700, Abhinav Kumar wrote:
> > Currently drm_atomic_print_state() internally allocates and uses a
> > drm_info printer. Allow it to accept any drm_printer type so that
> > the API can be leveraged even for taking drm snapshot.
> >
> > Signed-off-by: Abhinav Kumar <abhinavk@xxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/drm_atomic.c        | 17 ++++++++++++-----
> >  drivers/gpu/drm/drm_atomic_uapi.c   |  4 +++-
> >  drivers/gpu/drm/drm_crtc_internal.h |  4 +++-
> >  3 files changed, 18 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_atomic.c 
> > b/drivers/gpu/drm/drm_atomic.c
> > index 58527f151984..e7079a5f439c 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -1,6 +1,7 @@
> >  /*
> >   * Copyright (C) 2014 Red Hat
> >   * Copyright (C) 2014 Intel Corp.
> > + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> >   *
> >   * Permission is hereby granted, free of charge, to any person 
> > obtaining a
> >   * copy of this software and associated documentation files (the 
> > "Software"),
> > @@ -1543,9 +1544,9 @@ int __drm_atomic_helper_set_config(struct 
> > drm_mode_set *set,
> >  }
> >  EXPORT_SYMBOL(__drm_atomic_helper_set_config);
> >
> > -void drm_atomic_print_state(const struct drm_atomic_state *state)
> > +void drm_atomic_print_state(const struct drm_atomic_state *state,
> > +		struct drm_printer *p)
>
> Please add a nice kerneldoc for this newly exported function. 
> Specifically
> this kerneldoc needs to include a warning that state updates after call
> drm_atomic_state_helper_commit_hw_done() is unsafe to print using this
> function, because it looks at the new state objects. Only the old state
> structures will stay like this.
>
> So maybe rename the function to say print_new_state() to make this
> completely clear. That way we can eventually add a print_old_state() 
> when
> needed.
>
> Otherwise I think this makes sense, and nicely avoids the locking issue 
> of
> looking at ->state pointers without the right locking.
> -Daniel

Thanks for the review, I have addressed these comments and posted a V2.
-Abhinav

> >  {
> > -	struct drm_printer p = drm_info_printer(state->dev->dev);
> >  	struct drm_plane *plane;
> >  	struct drm_plane_state *plane_state;
> >  	struct drm_crtc *crtc;
> > @@ -1554,17 +1555,23 @@ void drm_atomic_print_state(const struct 
> > drm_atomic_state *state)
> >  	struct drm_connector_state *connector_state;
> >  	int i;
> >
> > +	if (!p) {
> > +		DRM_ERROR("invalid drm printer\n");
> > +		return;
> > +	}
> > +
> >  	DRM_DEBUG_ATOMIC("checking %p\n", state);
> >
> >  	for_each_new_plane_in_state(state, plane, plane_state, i)
> > -		drm_atomic_plane_print_state(&p, plane_state);
> > +		drm_atomic_plane_print_state(p, plane_state);
> >
> >  	for_each_new_crtc_in_state(state, crtc, crtc_state, i)
> > -		drm_atomic_crtc_print_state(&p, crtc_state);
> > +		drm_atomic_crtc_print_state(p, crtc_state);
> >
> >  	for_each_new_connector_in_state(state, connector, connector_state, 
> > i)
> > -		drm_atomic_connector_print_state(&p, connector_state);
> > +		drm_atomic_connector_print_state(p, connector_state);
> >  }
> > +EXPORT_SYMBOL(drm_atomic_print_state);
> >
> >  static void __drm_state_dump(struct drm_device *dev, struct 
> > drm_printer *p,
> >  			     bool take_locks)
> > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c 
> > b/drivers/gpu/drm/drm_atomic_uapi.c
> > index 25c269bc4681..d9ae86c92608 100644
> > --- a/drivers/gpu/drm/drm_atomic_uapi.c
> > +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> > @@ -2,6 +2,7 @@
> >   * Copyright (C) 2014 Red Hat
> >   * Copyright (C) 2014 Intel Corp.
> >   * Copyright (C) 2018 Intel Corp.
> > + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> >   *
> >   * Permission is hereby granted, free of charge, to any person 
> > obtaining a
> >   * copy of this software and associated documentation files (the 
> > "Software"),
> > @@ -1294,6 +1295,7 @@ int drm_mode_atomic_ioctl(struct drm_device 
> > *dev,
> >  	struct drm_out_fence_state *fence_state;
> >  	int ret = 0;
> >  	unsigned int i, j, num_fences;
> > +	struct drm_printer p = drm_info_printer(dev->dev);
> >
> >  	/* disallow for drivers not supporting atomic: */
> >  	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
> > @@ -1413,7 +1415,7 @@ int drm_mode_atomic_ioctl(struct drm_device 
> > *dev,
> >  		ret = drm_atomic_nonblocking_commit(state);
> >  	} else {
> >  		if (drm_debug_enabled(DRM_UT_STATE))
> > -			drm_atomic_print_state(state);
> > +			drm_atomic_print_state(state, &p);
> >
> >  		ret = drm_atomic_commit(state);
> >  	}
> > diff --git a/drivers/gpu/drm/drm_crtc_internal.h 
> > b/drivers/gpu/drm/drm_crtc_internal.h
> > index da96b2f64d7e..d34215366936 100644
> > --- a/drivers/gpu/drm/drm_crtc_internal.h
> > +++ b/drivers/gpu/drm/drm_crtc_internal.h
> > @@ -5,6 +5,7 @@
> >   *   Jesse Barnes <jesse.barnes@xxxxxxxxx>
> >   * Copyright © 2014 Intel Corporation
> >   *   Daniel Vetter <daniel.vetter@xxxxxxxx>
> > + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> >   *
> >   * Permission is hereby granted, free of charge, to any person 
> > obtaining a
> >   * copy of this software and associated documentation files (the 
> > "Software"),
> > @@ -233,7 +234,8 @@ int __drm_atomic_helper_disable_plane(struct 
> > drm_plane *plane,
> >  int __drm_atomic_helper_set_config(struct drm_mode_set *set,
> >  				   struct drm_atomic_state *state);
> >
> > -void drm_atomic_print_state(const struct drm_atomic_state *state);
> > +void drm_atomic_print_state(const struct drm_atomic_state *state,
> > +		struct drm_printer *p);
> >
> >  /* drm_atomic_uapi.c */
> >  int drm_atomic_connector_commit_dpms(struct drm_atomic_state *state,
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
> > Forum,
> > a Linux Foundation Collaborative Project
> >
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