Re: [PATCH v6 1/5] drm: Add function to convert rect in 16.16 fixed format to regular format

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Dec 15, 2020 at 03:43:00PM +0000, Souza, Jose wrote:
> On Tue, 2020-12-15 at 16:44 +0200, Ville Syrjälä wrote:
> > On Mon, Dec 14, 2020 at 09:49:08AM -0800, José Roberto de Souza wrote:
> > > Much more clear to read one function call than four lines doing this
> > > conversion.
> > > 
> > > Cc: dri-devel@lists.freedesktop.org
> > > Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > > ---
> > >  drivers/gpu/drm/drm_rect.c | 15 +++++++++++++++
> > >  include/drm/drm_rect.h     |  2 ++
> > >  2 files changed, 17 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
> > > index 0460e874896e..24345704b353 100644
> > > --- a/drivers/gpu/drm/drm_rect.c
> > > +++ b/drivers/gpu/drm/drm_rect.c
> > > @@ -373,3 +373,18 @@ void drm_rect_rotate_inv(struct drm_rect *r,
> > >  	}
> > >  }
> > >  EXPORT_SYMBOL(drm_rect_rotate_inv);
> > > +
> > > +/**
> > > + * drm_rect_convert_16_16_to_regular - Convert a rect in 16.16 fixed point form
> > > + * to regular form.
> > > + * @in: rect in 16.16 fixed point form
> > > + * @out: rect to be stored the converted value
> > > + */
> > > +void drm_rect_convert_16_16_to_regular(struct drm_rect *in, struct drm_rect *out)
> > > +{
> > > +	out->x1 = in->x1 >> 16;
> > > +	out->y1 = in->y1 >> 16;
> > > +	out->x2 = in->x2 >> 16;
> > > +	out->y2 = in->y2 >> 16;
> > > +}
> > 
> > That's not the same as what we do in most places. We truncate
> > the width/height, not x2/y2. Doing it on x2/y2 may increase
> > the width/height.
> > 
> > So I suggest something more like:
> > 
> > static inline void drm_rect_fp_to_int(struct drm_rect *r)
> > {
> > 	drm_rect_init(r, r->x1 >> 16, r->y1 >> 16,
> > 		      drm_rect_width(r) >> 16,
> > 		      drm_rect_height(r) >> 16);
> > }
> > 
> > to match the current way of doing things.
> 
> Okay, but most use cases takes drm_plane_state.src and converts and sets it in another rect, so will modify it to have two parameters.

Would seem a bit more generic by having the caller make the copy
if needed. But I guess not big deal either way.

At least make it follow the correct argument order as laid out
by memcpy() ;) (+const for the input argument ofc).

-- 
Ville Syrjälä
Intel
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