Message-ID: <4623f538-0ed5-2950-3d09-eea297219305@tronnes.org>
Date:	Fri, 10 Jun 2016 17:56:11 +0200
From:	Noralf Trønnes <noralf@...nnes.org>
To:	Daniel Vetter <daniel@...ll.ch>
Cc:	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	jsarha@...com
Subject: Re: [PATCH v5] drm: Add helper for simple display pipeline


Den 10.06.2016 17:34, skrev Daniel Vetter:
> On Fri, Jun 10, 2016 at 04:55:59PM +0200, Noralf Trønnes wrote:
>> Provides helper functions for drivers that have a simple display
>> pipeline. Plane, crtc and encoder are collapsed into one entity.
>>
>> Cc: jsarha@...com
>> Signed-off-by: Noralf Trønnes <noralf@...nnes.org>
>> ---
>>
>> Changes since v4:
>> - Remove drm_connector_register() call
>> - Forgot to assign pipe->connector
>>
>> Changes since v3:
>> - (struct drm_simple_display_pipe *)->funcs should be const
>>
>> Changes since v2:
>> - Drop Kconfig knob DRM_KMS_HELPER
>> - Expand documentation
>>
>> Changes since v1:
>> - Add DOC header and add to gpu.tmpl
>> - Fix docs: @funcs is optional, "negative error code",
>>    "This hook is optional."
>> - Add checks to drm_simple_kms_plane_atomic_check()
> Really nice work, and there's already 2-3 drivers in-flight that could
> benefit from this. I think there's some room for polish and small
> extensions, but much better when we do those once we have a few examples.
>
> Applied to drm-misc, thanks.
> -Daniel

Thanks for guiding me through.

Noralf.


>>   Documentation/DocBook/gpu.tmpl          |   6 +
>>   drivers/gpu/drm/Makefile                |   3 +-
>>   drivers/gpu/drm/drm_simple_kms_helper.c | 205 ++++++++++++++++++++++++++++++++
>>   include/drm/drm_simple_kms_helper.h     |  94 +++++++++++++++
>>   4 files changed, 307 insertions(+), 1 deletion(-)
>>   create mode 100644 drivers/gpu/drm/drm_simple_kms_helper.c
>>   create mode 100644 include/drm/drm_simple_kms_helper.h
>>
>> diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
>> index dac18b4..958d83c 100644
>> --- a/Documentation/DocBook/gpu.tmpl
>> +++ b/Documentation/DocBook/gpu.tmpl
>> @@ -1683,6 +1683,12 @@ void intel_crt_init(struct drm_device *dev)
>>   !Edrivers/gpu/drm/drm_panel.c
>>   !Pdrivers/gpu/drm/drm_panel.c drm panel
>>       </sect2>
>> +    <sect2>
>> +      <title>Simple KMS Helper Reference</title>
>> +!Iinclude/drm/drm_simple_kms_helper.h
>> +!Edrivers/gpu/drm/drm_simple_kms_helper.c
>> +!Pdrivers/gpu/drm/drm_simple_kms_helper.c overview
>> +    </sect2>
>>     </sect1>
>>
>>     <!-- Internals: kms properties -->
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index be43afb..9390df8 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -23,7 +23,8 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>>
>>   drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
>>   		drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
>> -		drm_kms_helper_common.o drm_dp_dual_mode_helper.o
>> +		drm_kms_helper_common.o drm_dp_dual_mode_helper.o \
>> +		drm_simple_kms_helper.o
>>
>>   drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
>>   drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
>> diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
>> new file mode 100644
>> index 0000000..b2071d4
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
>> @@ -0,0 +1,205 @@
>> +/*
>> + * Copyright (C) 2016 Noralf Trønnes
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + */
>> +
>> +#include <drm/drmP.h>
>> +#include <drm/drm_atomic.h>
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_crtc_helper.h>
>> +#include <drm/drm_plane_helper.h>
>> +#include <drm/drm_simple_kms_helper.h>
>> +#include <linux/slab.h>
>> +
>> +/**
>> + * DOC: overview
>> + *
>> + * This helper library provides helpers for drivers for simple display
>> + * hardware.
>> + *
>> + * drm_simple_display_pipe_init() initializes a simple display pipeline
>> + * which has only one full-screen scanout buffer feeding one output. The
>> + * pipeline is represented by struct &drm_simple_display_pipe and binds
>> + * together &drm_plane, &drm_crtc and &drm_encoder structures into one fixed
>> + * entity. Some flexibility for code reuse is provided through a separately
>> + * allocated &drm_connector object and supporting optional &drm_bridge
>> + * encoder drivers.
>> + */
>> +
>> +static const struct drm_encoder_funcs drm_simple_kms_encoder_funcs = {
>> +	.destroy = drm_encoder_cleanup,
>> +};
>> +
>> +static void drm_simple_kms_crtc_enable(struct drm_crtc *crtc)
>> +{
>> +	struct drm_simple_display_pipe *pipe;
>> +
>> +	pipe = container_of(crtc, struct drm_simple_display_pipe, crtc);
>> +	if (!pipe->funcs || !pipe->funcs->enable)
>> +		return;
>> +
>> +	pipe->funcs->enable(pipe, crtc->state);
>> +}
>> +
>> +static void drm_simple_kms_crtc_disable(struct drm_crtc *crtc)
>> +{
>> +	struct drm_simple_display_pipe *pipe;
>> +
>> +	pipe = container_of(crtc, struct drm_simple_display_pipe, crtc);
>> +	if (!pipe->funcs || !pipe->funcs->disable)
>> +		return;
>> +
>> +	pipe->funcs->disable(pipe);
>> +}
>> +
>> +static const struct drm_crtc_helper_funcs drm_simple_kms_crtc_helper_funcs = {
>> +	.disable = drm_simple_kms_crtc_disable,
>> +	.enable = drm_simple_kms_crtc_enable,
>> +};
>> +
>> +static const struct drm_crtc_funcs drm_simple_kms_crtc_funcs = {
>> +	.reset = drm_atomic_helper_crtc_reset,
>> +	.destroy = drm_crtc_cleanup,
>> +	.set_config = drm_atomic_helper_set_config,
>> +	.page_flip = drm_atomic_helper_page_flip,
>> +	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
>> +	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
>> +};
>> +
>> +static int drm_simple_kms_plane_atomic_check(struct drm_plane *plane,
>> +					struct drm_plane_state *plane_state)
>> +{
>> +	struct drm_rect src = {
>> +		.x1 = plane_state->src_x,
>> +		.y1 = plane_state->src_y,
>> +		.x2 = plane_state->src_x + plane_state->src_w,
>> +		.y2 = plane_state->src_y + plane_state->src_h,
>> +	};
>> +	struct drm_rect dest = {
>> +		.x1 = plane_state->crtc_x,
>> +		.y1 = plane_state->crtc_y,
>> +		.x2 = plane_state->crtc_x + plane_state->crtc_w,
>> +		.y2 = plane_state->crtc_y + plane_state->crtc_h,
>> +	};
>> +	struct drm_rect clip = { 0 };
>> +	struct drm_simple_display_pipe *pipe;
>> +	struct drm_crtc_state *crtc_state;
>> +	bool visible;
>> +	int ret;
>> +
>> +	pipe = container_of(plane, struct drm_simple_display_pipe, plane);
>> +	crtc_state = drm_atomic_get_existing_crtc_state(plane_state->state,
>> +							&pipe->crtc);
>> +	if (crtc_state->enable != !!plane_state->crtc)
>> +		return -EINVAL; /* plane must match crtc enable state */
>> +
>> +	if (!crtc_state->enable)
>> +		return 0; /* nothing to check when disabling or disabled */
>> +
>> +	clip.x2 = crtc_state->adjusted_mode.hdisplay;
>> +	clip.y2 = crtc_state->adjusted_mode.vdisplay;
>> +	ret = drm_plane_helper_check_update(plane, &pipe->crtc,
>> +					    plane_state->fb,
>> +					    &src, &dest, &clip,
>> +					    DRM_PLANE_HELPER_NO_SCALING,
>> +					    DRM_PLANE_HELPER_NO_SCALING,
>> +					    false, true, &visible);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (!visible)
>> +		return -EINVAL;
>> +
>> +	if (!pipe->funcs || !pipe->funcs->check)
>> +		return 0;
>> +
>> +	return pipe->funcs->check(pipe, plane_state, crtc_state);
>> +}
>> +
>> +static void drm_simple_kms_plane_atomic_update(struct drm_plane *plane,
>> +					struct drm_plane_state *pstate)
>> +{
>> +	struct drm_simple_display_pipe *pipe;
>> +
>> +	pipe = container_of(plane, struct drm_simple_display_pipe, plane);
>> +	if (!pipe->funcs || !pipe->funcs->update)
>> +		return;
>> +
>> +	pipe->funcs->update(pipe, pstate);
>> +}
>> +
>> +static const struct drm_plane_helper_funcs drm_simple_kms_plane_helper_funcs = {
>> +	.atomic_check = drm_simple_kms_plane_atomic_check,
>> +	.atomic_update = drm_simple_kms_plane_atomic_update,
>> +};
>> +
>> +static const struct drm_plane_funcs drm_simple_kms_plane_funcs = {
>> +	.update_plane		= drm_atomic_helper_update_plane,
>> +	.disable_plane		= drm_atomic_helper_disable_plane,
>> +	.destroy		= drm_plane_cleanup,
>> +	.reset			= drm_atomic_helper_plane_reset,
>> +	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
>> +	.atomic_destroy_state	= drm_atomic_helper_plane_destroy_state,
>> +};
>> +
>> +/**
>> + * drm_simple_display_pipe_init - Initialize a simple display pipeline
>> + * @dev: DRM device
>> + * @pipe: simple display pipe object to initialize
>> + * @funcs: callbacks for the display pipe (optional)
>> + * @formats: array of supported formats (%DRM_FORMAT_*)
>> + * @format_count: number of elements in @formats
>> + * @connector: connector to attach and register
>> + *
>> + * Sets up a display pipeline which consist of a really simple
>> + * plane-crtc-encoder pipe coupled with the provided connector.
>> + * Teardown of a simple display pipe is all handled automatically by the drm
>> + * core through calling drm_mode_config_cleanup(). Drivers afterwards need to
>> + * release the memory for the structure themselves.
>> + *
>> + * Returns:
>> + * Zero on success, negative error code on failure.
>> + */
>> +int drm_simple_display_pipe_init(struct drm_device *dev,
>> +			struct drm_simple_display_pipe *pipe,
>> +			const struct drm_simple_display_pipe_funcs *funcs,
>> +			const uint32_t *formats, unsigned int format_count,
>> +			struct drm_connector *connector)
>> +{
>> +	struct drm_encoder *encoder = &pipe->encoder;
>> +	struct drm_plane *plane = &pipe->plane;
>> +	struct drm_crtc *crtc = &pipe->crtc;
>> +	int ret;
>> +
>> +	pipe->connector = connector;
>> +	pipe->funcs = funcs;
>> +
>> +	drm_plane_helper_add(plane, &drm_simple_kms_plane_helper_funcs);
>> +	ret = drm_universal_plane_init(dev, plane, 0,
>> +				       &drm_simple_kms_plane_funcs,
>> +				       formats, format_count,
>> +				       DRM_PLANE_TYPE_PRIMARY, NULL);
>> +	if (ret)
>> +		return ret;
>> +
>> +	drm_crtc_helper_add(crtc, &drm_simple_kms_crtc_helper_funcs);
>> +	ret = drm_crtc_init_with_planes(dev, crtc, plane, NULL,
>> +					&drm_simple_kms_crtc_funcs, NULL);
>> +	if (ret)
>> +		return ret;
>> +
>> +	encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
>> +	ret = drm_encoder_init(dev, encoder, &drm_simple_kms_encoder_funcs,
>> +			       DRM_MODE_ENCODER_NONE, NULL);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return drm_mode_connector_attach_encoder(connector, encoder);
>> +}
>> +EXPORT_SYMBOL(drm_simple_display_pipe_init);
>> +
>> +MODULE_LICENSE("GPL");
>> diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
>> new file mode 100644
>> index 0000000..2690397
>> --- /dev/null
>> +++ b/include/drm/drm_simple_kms_helper.h
>> @@ -0,0 +1,94 @@
>> +/*
>> + * Copyright (C) 2016 Noralf Trønnes
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + */
>> +
>> +#ifndef __LINUX_DRM_SIMPLE_KMS_HELPER_H
>> +#define __LINUX_DRM_SIMPLE_KMS_HELPER_H
>> +
>> +struct drm_simple_display_pipe;
>> +
>> +/**
>> + * struct drm_simple_display_pipe_funcs - helper operations for a simple
>> + *                                        display pipeline
>> + */
>> +struct drm_simple_display_pipe_funcs {
>> +	/**
>> +	 * @enable:
>> +	 *
>> +	 * This function should be used to enable the pipeline.
>> +	 * It is called when the underlying crtc is enabled.
>> +	 * This hook is optional.
>> +	 */
>> +	void (*enable)(struct drm_simple_display_pipe *pipe,
>> +		       struct drm_crtc_state *crtc_state);
>> +	/**
>> +	 * @disable:
>> +	 *
>> +	 * This function should be used to disable the pipeline.
>> +	 * It is called when the underlying crtc is disabled.
>> +	 * This hook is optional.
>> +	 */
>> +	void (*disable)(struct drm_simple_display_pipe *pipe);
>> +
>> +	/**
>> +	 * @check:
>> +	 *
>> +	 * This function is called in the check phase of an atomic update,
>> +	 * specifically when the underlying plane is checked.
>> +	 * The simple display pipeline helpers already check that the plane is
>> +	 * not scaled, fills the entire visible area and is always enabled
>> +	 * when the crtc is also enabled.
>> +	 * This hook is optional.
>> +	 *
>> +	 * RETURNS:
>> +	 *
>> +	 * 0 on success, -EINVAL if the state or the transition can't be
>> +	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
>> +	 * attempt to obtain another state object ran into a &drm_modeset_lock
>> +	 * deadlock.
>> +	 */
>> +	int (*check)(struct drm_simple_display_pipe *pipe,
>> +		     struct drm_plane_state *plane_state,
>> +		     struct drm_crtc_state *crtc_state);
>> +	/**
>> +	 * @update:
>> +	 *
>> +	 * This function is called when the underlying plane state is updated.
>> +	 * This hook is optional.
>> +	 */
>> +	void (*update)(struct drm_simple_display_pipe *pipe,
>> +		       struct drm_plane_state *plane_state);
>> +};
>> +
>> +/**
>> + * struct drm_simple_display_pipe - simple display pipeline
>> + * @crtc: CRTC control structure
>> + * @plane: Plane control structure
>> + * @encoder: Encoder control structure
>> + * @connector: Connector control structure
>> + * @funcs: Pipeline control functions (optional)
>> + *
>> + * Simple display pipeline with plane, crtc and encoder collapsed into one
>> + * entity. It should be initialized by calling drm_simple_display_pipe_init().
>> + */
>> +struct drm_simple_display_pipe {
>> +	struct drm_crtc crtc;
>> +	struct drm_plane plane;
>> +	struct drm_encoder encoder;
>> +	struct drm_connector *connector;
>> +
>> +	const struct drm_simple_display_pipe_funcs *funcs;
>> +};
>> +
>> +int drm_simple_display_pipe_init(struct drm_device *dev,
>> +			struct drm_simple_display_pipe *pipe,
>> +			const struct drm_simple_display_pipe_funcs *funcs,
>> +			const uint32_t *formats, unsigned int format_count,
>> +			struct drm_connector *connector);
>> +
>> +#endif /* __LINUX_DRM_SIMPLE_KMS_HELPER_H */
>> --
>> 2.8.2
>>

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