Message-ID: <d4858d19-bdf7-d8d6-0668-a2789f8b5d23@tronnes.org>
Date:	Tue, 17 May 2016 14:22:26 +0200
From:	Noralf Trønnes <noralf@...nnes.org>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:	Daniel Vetter <daniel@...ll.ch>, jsarha@...com,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/3] drm: Add helper for simple display pipeline



Den 17.05.2016 14:12, skrev Ville Syrjälä:
> On Tue, May 17, 2016 at 02:00:45PM +0200, Noralf Trønnes wrote:
>> Den 17.05.2016 09:59, skrev Daniel Vetter:
>>> On Tue, May 17, 2016 at 10:46:51AM +0300, Ville Syrjälä wrote:
>>>> On Tue, May 17, 2016 at 09:05:01AM +0200, Daniel Vetter wrote:
>>>>> On Thu, May 12, 2016 at 09:36:14PM +0300, Ville Syrjälä wrote:
>>>>>> On Thu, May 12, 2016 at 08:25:23PM +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 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()
>>>>>>>
>>>>>>>    Documentation/DocBook/gpu.tmpl          |   6 +
>>>>>>>    drivers/gpu/drm/Makefile                |   2 +-
>>>>>>>    drivers/gpu/drm/drm_simple_kms_helper.c | 208 ++++++++++++++++++++++++++++++++
>>>>>>>    include/drm/drm_simple_kms_helper.h     |  94 +++++++++++++++
>>>>>>>    4 files changed, 309 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 4a0c599..cf3f5a8 100644
>>>>>>> --- a/Documentation/DocBook/gpu.tmpl
>>>>>>> +++ b/Documentation/DocBook/gpu.tmpl
>>>>>>> @@ -1693,6 +1693,12 @@ 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 2bd3e5a..31b85df5 100644
>>>>>>> --- a/drivers/gpu/drm/Makefile
>>>>>>> +++ b/drivers/gpu/drm/Makefile
>>>>>>> @@ -23,7 +23,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>>>>>>>
>>>>>>>    drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
>>>>>>>    		drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
>>>>>>> -		drm_kms_helper_common.o
>>>>>>> +		drm_kms_helper_common.o drm_simple_kms_helper.o
>>>>>>>
>>>>>>>    drm_kms_helper-$(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..d45417a
>>>>>>> --- /dev/null
>>>>>>> +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
>>>>>>> @@ -0,0 +1,208 @@
>>>>>>> +/*
>>>>>>> + * 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);
>>>>>>> +}
>>>>>> What's anyone supposed to do with this when the clipped coordinates
>>>>>> aren't even passed/stored anywhere?
>>>>> It disallows positioning and scaling, so shouldn't ever need to have the
>>>>> clipped area?
>>>> You can still configure a larger area that gets clipped to the
>>>> fullscreen dimensions.
>>> Oh right. Noralf, sounds like we need to feed back the clipped rectangle.
>>> Probably best if we add clipped plane coordinates to drm_plane_state.
>> Both src and crtc or only src?
>>
>>        if (!visible)
>>            return -EINVAL;
>> +
>> +    plane_state->src_x = src.x1;
>> +    plane_state->src_y = src.y1;
>> +    plane_state->src_w = drm_rect_width(&src);
>> +    plane_state->src_h = drm_rect_height(&src);
>> +
>> +    plane_state->crtc_x = dest.x1;
>> +    plane_state->crtc_y = dest.y1;
>> +    plane_state->crtc_w = drm_rect_width(&dest);
>> +    plane_state->crtc_h = drm_rect_height(&dest);
> You aren't allowed clobber the user provided coordinates like this.
> What you need to do is store the clipped coordinates in the plane
> state in addition to the user coordinates.

How do I do that?

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