On Wed, Feb 07, 2018 at 01:41:18AM +0000, Pandiyan, Dhinakaran wrote: > On Fri, 2018-02-02 at 21:12 -0800, Dhinakaran Pandiyan wrote: > > 570e86963a51 ("drm: Widen vblank count to 64-bits [v3]") changed the > > return type for drm_crtc_vblank_count() to u64. This could cause > > potential problems if the return value is used in arithmetic operations > > with a 32-bit reference HW vblank count. Explicitly typecasting this > > down to u32 either fixes a potential problem or serves to add clarity in > > case the implicit typecasting was already correct. > > > > Cc: Keith Packard <keithp@xxxxxxxxxx> > > Cc: Thierry Reding <treding@xxxxxxxxxx> > > > Thierry, > > Can I get an Ack on this please? > > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx> > > --- > > drivers/gpu/drm/tegra/dc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c > > index b8403ed48285..49df2db2ad46 100644 > > --- a/drivers/gpu/drm/tegra/dc.c > > +++ b/drivers/gpu/drm/tegra/dc.c > > @@ -1359,7 +1359,7 @@ static u32 tegra_dc_get_vblank_counter(struct drm_crtc *crtc) > > return host1x_syncpt_read(dc->syncpt); > > > > /* fallback to software emulated VBLANK counter */ > > - return drm_crtc_vblank_count(&dc->base); > > + return (u32)drm_crtc_vblank_count(&dc->base); Isn't this the wrong way around? Shouldn't we instead make the ->get_vblank_counter() callback return u64 like drm_crtc_vblank_count()? Thierry
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