[PATCH 1/7] drm/arc: Stop consulting plane->fb

[Daniel Vetter]

On Thu, Apr 05, 2018 at 11:19:44PM +0300, Ville Syrjälä wrote:
> On Thu, Apr 05, 2018 at 10:08:57PM +0200, Daniel Vetter wrote:
> > On Thu, Apr 05, 2018 at 10:50:29PM +0300, Ville Syrjala wrote:
> > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > 
> > > We want to stop using plane->fb with atomic driver, so stop looking at
> > > it.
> > > 
> > > I have no idea what this code is trying to achieve. There is no
> > > corresponding check in the enable path. Also since
> > > arc_pgu_set_pxl_fmt() will anyway oops if there is no fb I'm going
> > > to assuming that I can just remove the check entirely. There seems
> > > to be a general shortage of .atomic_check() in this driver...
> > 
> > I think arcpgu is the perfect example of a small driver that _really_
> > wants to use drm_simple_display_pipe_helper. Which would address the
> > outright lack of any and all atomic_check code (beyond basic mode
> > validation through mode_valid).
> > 
> > I also just noticed that it still has a bunch of the legacy hooks set,
> > e.g. mode_set, mode_set_base are all no longer used in atomic.
> > 
> > I think the code won't be able to oops, since if there's no fb, we don't
> > enable the plane (and it happily allows that), so should be all
> > non-oopsing. Even with this check here removed.
> 
> arc_pgu_set_pxl_fmt() gets called from the .mode_set_nofb() hook
> which I assume doesn't care about planes at all. So to me it looks like
> it'll definitely oops.

Indeed, I was blind. Commit message looks good.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> 
> > 
> > Ofc the hw might get pissed at us in this case, but I can't tell that.
> > Like I said, conversion to drm_simple_display_pipe_helper is probably the
> > way to go.
> > 
> > Anyway, this patch here looks good, if you adjust the commit message to
> > explain why it can't oops:
> > 
> > Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > 
> > > 
> > > Cc: Alexey Brodkin <abrodkin at synopsys.com>
> > > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/arc/arcpgu_crtc.c | 3 ---
> > >  1 file changed, 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/arc/arcpgu_crtc.c b/drivers/gpu/drm/arc/arcpgu_crtc.c
> > > index 16903dc7fe0d..c3349b8fb58b 100644
> > > --- a/drivers/gpu/drm/arc/arcpgu_crtc.c
> > > +++ b/drivers/gpu/drm/arc/arcpgu_crtc.c
> > > @@ -136,9 +136,6 @@ static void arc_pgu_crtc_atomic_disable(struct drm_crtc *crtc,
> > >  {
> > >  	struct arcpgu_drm_private *arcpgu = crtc_to_arcpgu_priv(crtc);
> > >  
> > > -	if (!crtc->primary->fb)
> > > -		return;
> > > -
> > >  	clk_disable_unprepare(arcpgu->clk);
> > >  	arc_pgu_write(arcpgu, ARCPGU_REG_CTRL,
> > >  			      arc_pgu_read(arcpgu, ARCPGU_REG_CTRL) &
> > > -- 
> > > 2.16.1
> > > 
> > 
> > -- 
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> 
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch