linux-kernel - Re: [Intel-gfx] [PATCH v2 38/39] drm/i915: add descriptions for some RPM macros at intel_gt

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Date:   Tue, 9 Aug 2022 06:12:06 -0400
From:   Rodrigo Vivi <rodrigo.vivi@...el.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
CC:     Thomas Zimmermann <tzimmermann@...e.de>,
        Jonathan Corbet <corbet@....net>,
        David Airlie <airlied@...ux.ie>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, Maxime Ripard <mripard@...nel.org>,
        <intel-gfx@...ts.freedesktop.org>
Subject: Re: [Intel-gfx] [PATCH v2 38/39] drm/i915: add descriptions for some
 RPM macros at intel_gt_pm.h

On Wed, Jul 13, 2022 at 09:12:26AM +0100, Mauro Carvalho Chehab wrote:
> The intel_gt_pm.h file contains some convenient macros to be used
> in GT code in order to get/put runtime PM references and for
> checking them.
> 
> Add descriptions based on the ones at intel_wakeref.h and
> intel_runtime_pm.c.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@...nel.org>
> ---
> 
> To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
> See [PATCH v2 00/39] at: https://lore.kernel.org/all/cover.1657699522.git.mchehab@kernel.org/
> 
>  Documentation/gpu/i915.rst            |  2 +
>  drivers/gpu/drm/i915/gt/intel_gt_pm.h | 62 +++++++++++++++++++++++++++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
> index 6bb50edc6d79..9862d504df4d 100644
> --- a/Documentation/gpu/i915.rst
> +++ b/Documentation/gpu/i915.rst
> @@ -709,6 +709,8 @@ Table Manager (TTM)
>  
>  .. kernel-doc:: drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
>  
> +.. kernel-doc:: drivers/gpu/drm/i915/gt/intel_gt_pm.h

I don't believe this is the right placement for this.

the rest lgtm

> +
>  Graphics Execution Manager (GEM)
>  --------------------------------
>  
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> index bc898df7a48c..a8ea6846980a 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
> @@ -11,21 +11,57 @@
>  #include "intel_gt_types.h"
>  #include "intel_wakeref.h"
>  
> +/**
> + * intel_gt_pm_is_awake: Query whether the runtime PM is awake held
> + *
> + * @gt: pointer to the graphics engine
> + *
> + * Returns: true if a runtime pm reference is currently held and the GT is
> + * awake.
> + */
>  static inline bool intel_gt_pm_is_awake(const struct intel_gt *gt)
>  {
>  	return intel_wakeref_is_active(&gt->wakeref);
>  }
>  
> +/**
> + * intel_gt_pm_get: grab a runtime PM reference ensuring that GT is powered up
> + * @gt: pointer to the graphics engine
> + *
> + * Any runtime pm reference obtained by this function must have a symmetric
> + * call to intel_gt_pm_put() to release the reference again.
> + *
> + * Note that this is allowed to fail, in which case the runtime-pm wakeref
> + * will be released and the acquisition unwound.
> + */
>  static inline void intel_gt_pm_get(struct intel_gt *gt)
>  {
>  	intel_wakeref_get(&gt->wakeref);
>  }
>  
> +/**
> + * __intel_gt_pm_get: Acquire the runtime PM reference again
> + * @gt: pointer to the graphics engine which contains the wakeref
> + *
> + * Increment the PM reference counter, only valid if it is already held by
> + * the caller.
> + *
> + * See intel_gt_pm_get().
> + */
>  static inline void __intel_gt_pm_get(struct intel_gt *gt)
>  {
>  	__intel_wakeref_get(&gt->wakeref);
>  }
>  
> +/**
> + * intel_gt_pm_get_if_awake: Acquire the runtime PM reference if active
> + * @gt: pointer to the graphics engine which contains the PM reference
> + *
> + * Acquire a hold on the PM reference, but only if the GT is already
> + * active.
> + *
> + * Returns: true if the wakeref was acquired, false otherwise.
> + */
>  static inline bool intel_gt_pm_get_if_awake(struct intel_gt *gt)
>  {
>  	return intel_wakeref_get_if_active(&gt->wakeref);
> @@ -36,6 +72,14 @@ static inline void intel_gt_pm_might_get(struct intel_gt *gt)
>  	intel_wakeref_might_get(&gt->wakeref);
>  }
>  
> +/**
> + * intel_gt_pm_put: Release the runtime PM reference
> + * @gt: pointer to the graphics engine which contains the PM reference
> + *
> + * Release our hold on the runtime PM for GT.
> + *
> + * It might power down the GT right away if this is the last reference.
> + */
>  static inline void intel_gt_pm_put(struct intel_gt *gt)
>  {
>  	intel_wakeref_put(&gt->wakeref);
> @@ -51,10 +95,28 @@ static inline void intel_gt_pm_might_put(struct intel_gt *gt)
>  	intel_wakeref_might_put(&gt->wakeref);
>  }
>  
> +/**
> + * with_intel_gt_pm - get a GT reference ensuring that GT is powered up,
> + *	run some code and then put the reference away.
> + *
> + * @gt: pointer to the gt
> + * @tmp: pointer to a temporary wakeref.
> + */
>  #define with_intel_gt_pm(gt, tmp) \
>  	for (tmp = 1, intel_gt_pm_get(gt); tmp; \
>  	     intel_gt_pm_put(gt), tmp = 0)
>  
> +/**
> + * intel_gt_pm_wait_for_idle: Wait until the runtime PM reference is idle
> + * @gt: pointer to the graphics engine which contains the PM reference
> + *
> + * Wait for the earlier asynchronous release of the runtime PM reference. Note
> + * this will wait for any third party as well, so make sure you only wait
> + * when you have control over the GT runtime PM and trust no one else is
> + * acquiring it.
> + *
> + * Return: 0 on success, error code if killed.
> + */
>  static inline int intel_gt_pm_wait_for_idle(struct intel_gt *gt)
>  {
>  	return intel_wakeref_wait_for_idle(&gt->wakeref);
> -- 
> 2.36.1
>