[PATCH 1/9] drm: add flip-work helper

[Daniel Vetter]

On Wed, Aug 07, 2013 at 01:41:19PM -0400, Rob Clark wrote:
> A small helper to queue up work to do, from workqueue context, after a
> flip.  Typically useful to defer unreffing buffers that may be read by
> the display controller until vblank.
> 
> Signed-off-by: Rob Clark <robdclark at gmail.com>

Since you have this nice kerneldoc already here, can you please integrate
it all into the drm DocBook where all the other helpers are?

I don't think I'll use these for i915, but I can see that they're useful
for simple kms drivers. So

Acked-by: Daniel Vetter <daniel.vetter at ffwll.ch>

if the DocBook gets wired up.

Cheers, Daniel


> ---
>  drivers/gpu/drm/Makefile        |   2 +-
>  drivers/gpu/drm/drm_flip_work.c | 124 ++++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_flip_work.h     |  71 +++++++++++++++++++++++
>  3 files changed, 196 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/drm_flip_work.c
>  create mode 100644 include/drm/drm_flip_work.h
> 
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index d943b94..2aaf082 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -13,7 +13,7 @@ drm-y       :=	drm_auth.o drm_buffer.o drm_bufs.o drm_cache.o \
>  		drm_crtc.o drm_modes.o drm_edid.o \
>  		drm_info.o drm_debugfs.o drm_encoder_slave.o \
>  		drm_trace_points.o drm_global.o drm_prime.o \
> -		drm_rect.o drm_vma_manager.o
> +		drm_rect.o drm_vma_manager.o drm_flip_work.o
>  
>  drm-$(CONFIG_COMPAT) += drm_ioc32.o
>  drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o
> diff --git a/drivers/gpu/drm/drm_flip_work.c b/drivers/gpu/drm/drm_flip_work.c
> new file mode 100644
> index 0000000..e788882
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_flip_work.c
> @@ -0,0 +1,124 @@
> +/*
> + * Copyright (C) 2013 Red Hat
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> + * SOFTWARE.
> + */
> +
> +#include "drmP.h"
> +#include "drm_flip_work.h"
> +
> +/**
> + * drm_flip_work_queue - queue work
> + * @work: the flip-work
> + * @val: the value to queue
> + *
> + * Queues work, that will later be run (passed back to drm_flip_func_t
> + * func) on a work queue after drm_flip_work_commit() is called.
> + */
> +void drm_flip_work_queue(struct drm_flip_work *work, void *val)
> +{
> +	if (kfifo_put(&work->fifo, (const void **)&val)) {
> +		atomic_inc(&work->pending);
> +	} else {
> +		DRM_ERROR("%s fifo full!\n", work->name);
> +		work->func(work, val);
> +	}
> +}
> +EXPORT_SYMBOL(drm_flip_work_queue);
> +
> +/**
> + * drm_flip_work_commit - commit queued work
> + * @work: the flip-work
> + * @wq: the work-queue to run the queued work on
> + *
> + * Trigger work previously queued by drm_flip_work_queue() to run
> + * on a workqueue.  The typical usage would be to queue work (via
> + * drm_flip_work_queue()) at any point (from vblank irq and/or
> + * prior), and then from vblank irq commit the queued work.
> + */
> +void drm_flip_work_commit(struct drm_flip_work *work,
> +		struct workqueue_struct *wq)
> +{
> +	uint32_t pending = atomic_read(&work->pending);
> +	atomic_add(pending, &work->count);
> +	atomic_sub(pending, &work->pending);
> +	queue_work(wq, &work->worker);
> +}
> +EXPORT_SYMBOL(drm_flip_work_commit);
> +
> +static void flip_worker(struct work_struct *w)
> +{
> +	struct drm_flip_work *work = container_of(w, struct drm_flip_work, worker);
> +	uint32_t count = atomic_read(&work->count);
> +	void *val = NULL;
> +
> +	atomic_sub(count, &work->count);
> +
> +	while(count--)
> +		if (!WARN_ON(!kfifo_get(&work->fifo, &val)))
> +			work->func(work, val);
> +}
> +
> +/**
> + * drm_flip_work_init - initialize flip-work
> + * @work: the flip-work to initialize
> + * @size: the max queue depth
> + * @name: debug name
> + * @func: the callback work function
> + *
> + * Initializes/allocates resources for the flip-work
> + *
> + * RETURNS:
> + * Zero on success, error code on failure.
> + */
> +int drm_flip_work_init(struct drm_flip_work *work, int size,
> +		const char *name, drm_flip_func_t func)
> +{
> +	int ret;
> +
> +	work->name = name;
> +	atomic_set(&work->count, 0);
> +	atomic_set(&work->pending, 0);
> +	work->func = func;
> +
> +	ret = kfifo_alloc(&work->fifo, size, GFP_KERNEL);
> +	if (ret) {
> +		DRM_ERROR("could not allocate %s fifo\n", name);
> +		return ret;
> +	}
> +
> +	INIT_WORK(&work->worker, flip_worker);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_flip_work_init);
> +
> +/**
> + * drm_flip_work_cleanup - cleans up flip-work
> + * @work: the flip-work to cleanup
> + *
> + * Destroy resources allocated for the flip-work
> + */
> +void drm_flip_work_cleanup(struct drm_flip_work *work)
> +{
> +	WARN_ON(!kfifo_is_empty(&work->fifo));
> +	kfifo_free(&work->fifo);
> +}
> +EXPORT_SYMBOL(drm_flip_work_cleanup);
> diff --git a/include/drm/drm_flip_work.h b/include/drm/drm_flip_work.h
> new file mode 100644
> index 0000000..7d3840b
> --- /dev/null
> +++ b/include/drm/drm_flip_work.h
> @@ -0,0 +1,71 @@
> +/*
> + * Copyright (C) 2013 Red Hat
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> + * SOFTWARE.
> + */
> +
> +#ifndef DRM_FLIP_WORK_H
> +#define DRM_FLIP_WORK_H
> +
> +#include <linux/kfifo.h>
> +#include <linux/workqueue.h>
> +
> +/**
> + * DOC: flip utils
> + *
> + * Util to queue up work to run from work-queue context after flip/vblank.
> + * Typically this can be used to defer unref of framebuffer's, cursor
> + * bo's, etc until after vblank.  The APIs are all safe (and lockless)
> + * for up to one producer and once consumer at a time.  The single-consumer
> + * aspect is ensured by committing the queued work to a single work-queue.
> + */
> +
> +struct drm_flip_work;
> +
> +/**
> + * drm_flip_func_t - callback function
> + *
> + * @work: the flip work
> + * @val: value queued via drm_flip_work_queue()
> + *
> + * Callback function to be called for each of the  queue'd work items after
> + * drm_flip_work_commit() is called.
> + */
> +typedef void (*drm_flip_func_t)(struct drm_flip_work *work, void *val);
> +
> +/**
> + * struct drm_flip_work - flip work queue
> + */
> +struct drm_flip_work {
> +	const char *name;
> +	atomic_t pending, count;
> +	drm_flip_func_t func;
> +	struct work_struct worker;
> +	DECLARE_KFIFO_PTR(fifo, void *);
> +};
> +
> +void drm_flip_work_queue(struct drm_flip_work *work, void *val);
> +void drm_flip_work_commit(struct drm_flip_work *work,
> +		struct workqueue_struct *wq);
> +int drm_flip_work_init(struct drm_flip_work *work, int size,
> +		const char *name, drm_flip_func_t func);
> +void drm_flip_work_cleanup(struct drm_flip_work *work);
> +
> +#endif  /* DRM_FLIP_WORK_H */
> -- 
> 1.8.3.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch