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

[abhinavk@codeaurora.org]

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@codeaurora.org>
>> ---
>>  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@intel.com>
>>   * Copyright © 2014 Intel Corporation
>>   *   Daniel Vetter <daniel.vetter@ffwll.ch>
>> + * 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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