Re: [PATCH v4 3/3] drm: Add helper for simple display pipeline

From: Ville Syrjälä
Date: Tue May 17 2016 - 03:47:09 EST


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@xxxxxx
> > > Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
> > > ---
> > >
> > > 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.

--
Ville Syrjälä
Intel OTC