Re: [PATCH 3/9] drm/plane-helper: Add drm_plane_helper_check_state()

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/9] drm/plane-helper: Add drm_plane_helper_check_state()
Date: Tue, 26 Jul 2016 19:42:16 +0300	[thread overview]
Message-ID: <20160726164216.GK4329@intel.com> (raw)
In-Reply-To: <20160726163329.GC31051@nuc-i3427.alporthouse.com>

On Tue, Jul 26, 2016 at 05:33:29PM +0100, Chris Wilson wrote:
> On Tue, Jul 26, 2016 at 07:06:58PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Add a version of drm_plane_helper_check_update() which takes a plane
> > state instead of having the caller pass in everything.
> > 
> > And to reduce code duplication, let's reimplement
> > drm_plane_helper_check_update() in terms of the new function, by
> > having a tempororary plane state on the stack.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/drm_plane_helper.c | 136 ++++++++++++++++++++++++++++---------
> >  include/drm/drm_plane_helper.h     |   5 ++
> >  2 files changed, 110 insertions(+), 31 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
> > index 16c4a7bd7465..1124eb827671 100644
> > --- a/drivers/gpu/drm/drm_plane_helper.c
> > +++ b/drivers/gpu/drm/drm_plane_helper.c
> > @@ -108,14 +108,9 @@ static int get_connectors_for_crtc(struct drm_crtc *crtc,
> >  }
> >  
> >  /**
> > - * drm_plane_helper_check_update() - Check plane update for validity
> > - * @plane: plane object to update
> > - * @crtc: owning CRTC of owning plane
> > - * @fb: framebuffer to flip onto plane
> > - * @src: source coordinates in 16.16 fixed point
> > - * @dest: integer destination coordinates
> > + * drm_plane_helper_check_state() - Check plane state for validity
> > + * @state: plane state to check
> >   * @clip: integer clipping coordinates
> > - * @rotation: plane rotation
> >   * @min_scale: minimum @src:@dest scaling factor in 16.16 fixed point
> >   * @max_scale: maximum @src:@dest scaling factor in 16.16 fixed point
> >   * @can_position: is it legal to position the plane such that it
> > @@ -123,8 +118,6 @@ static int get_connectors_for_crtc(struct drm_crtc *crtc,
> >   *                only be false for primary planes.
> >   * @can_update_disabled: can the plane be updated while the crtc
> >   *                       is disabled?
> > - * @visible: output parameter indicating whether plane is still visible after
> > - *           clipping
> >   *
> >   * Checks that a desired plane update is valid.  Drivers that provide
> >   * their own plane handling rather than helper-provided implementations may
> > @@ -134,29 +127,38 @@ static int get_connectors_for_crtc(struct drm_crtc *crtc,
> >   * RETURNS:
> >   * Zero if update appears valid, error code on failure
> >   */
> > -int drm_plane_helper_check_update(struct drm_plane *plane,
> > -				  struct drm_crtc *crtc,
> > -				  struct drm_framebuffer *fb,
> > -				  struct drm_rect *src,
> > -				  struct drm_rect *dest,
> > -				  const struct drm_rect *clip,
> > -				  unsigned int rotation,
> > -				  int min_scale,
> > -				  int max_scale,
> > -				  bool can_position,
> > -				  bool can_update_disabled,
> > -				  bool *visible)
> > +int drm_plane_helper_check_state(struct drm_plane_state *state,
> > +				 const struct drm_rect *clip,
> > +				 int min_scale,
> > +				 int max_scale,
> > +				 bool can_position,
> > +				 bool can_update_disabled)
> >  {
> > +	struct drm_crtc *crtc = state->crtc;
> > +	struct drm_framebuffer *fb = state->fb;
> > +	struct drm_rect *src = &state->src;
> > +	struct drm_rect *dst = &state->dst;
> > +	unsigned int rotation = state->rotation;
> >  	int hscale, vscale;
> >  
> > +	src->x1 = state->src_x;
> > +	src->y1 = state->src_y;
> > +	src->x2 = state->src_x + state->src_w;
> > +	src->y2 = state->src_y + state->src_h;
> > +
> > +	dst->x1 = state->crtc_x;
> > +	dst->y1 = state->crtc_y;
> > +	dst->x2 = state->crtc_x + state->crtc_w;
> > +	dst->y2 = state->crtc_y + state->crtc_h;
> 
> It's a little surprising to me that the check writes fields into the
> drm_plane_state. Care to at least mention the side-effects in the kernel
> doc?

That's a lot of what the atomic "check" functions do. A bit of a bad
naming convention that. Not sure who came up with it. Should probably
rename them all to "compute" or something.

But I can at leat expand the docs here a bit in the meantime.

-- 
Ville Syrjälä
Intel OTC
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