[PATCH] drm: Print erroneous hscale/vscale on failure

[Sean Paul]

On Thu, Sep 06, 2018 at 02:30:24PM +0300, Ville Syrjälä wrote:
> On Wed, Sep 05, 2018 at 04:46:01PM -0400, Sean Paul wrote:
> > From: Sean Paul <seanpaul at chromium.org>
> > 
> > I ran across this last week when I was trying to get this function to
> > work. It's useful to have the scale values in the log upon failure.
> > 
> > Signed-off-by: Sean Paul <seanpaul at chromium.org>
> > ---
> >  drivers/gpu/drm/drm_atomic_helper.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index 2c23a48482da..1725546d5105 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -758,7 +758,8 @@ int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state,
> >  	hscale = drm_rect_calc_hscale(src, dst, min_scale, max_scale);
> >  	vscale = drm_rect_calc_vscale(src, dst, min_scale, max_scale);
> >  	if (hscale < 0 || vscale < 0) {
> > -		DRM_DEBUG_KMS("Invalid scaling of plane\n");
> > +		DRM_DEBUG_KMS("Invalid scaling of plane (%d/%d)\n",
> > +			      hscale, vscale);
> 
> I think it's just going to be -ERANGE for at least one of them.
> So not quite sure what extra benefit we get from this. What
> might be more helpful is printing the actual computed scale
> factor and the min/max.

Good point, it will tell you which scale is invalid, but not necessarily why.
I'll tweak the args for drm_rect_calc_*scale to return -errno and pass *scale by
pointer.

v2 incoming

Sean

> 
> >  		drm_rect_debug_print("src: ", &plane_state->src, true);
> >  		drm_rect_debug_print("dst: ", &plane_state->dst, false);
> >  		return -ERANGE;
> > -- 
> > Sean Paul, Software Engineer, Google / Chromium OS
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Ville Syrjälä
> Intel

-- 
Sean Paul, Software Engineer, Google / Chromium OS