[PATCH RFC] drm/atomic: Fall back to legacy call back in *_connector_dpms()

[Ville Syrjälä]

On Fri, Feb 12, 2016 at 07:08:46PM +0200, Tomi Valkeinen wrote:
> On 12/02/16 17:34, Daniel Vetter wrote:
> > On Fri, Feb 12, 2016 at 05:17:19PM +0200, Jyri Sarha wrote:
> >> Fall back to legacy drm_helper_connector_dpms() call back in
> >> drm_atomic_helper_connector_dpms() if DRIVER_ATOMIC feature is not
> >> present.
> >>
> >> Calling drm_atomic_helper_connector_dpms() from non atomic driver
> >> causes undefined behavior. This is a problem with componentized
> >> encoder/connector drivers that may be bound to both atomic and
> >> non atomic drivers.
> >>
> >> Signed-off-by: Jyri Sarha <jsarha at ti.com>
> >> ---
> >> This is just an alternative to this:
> >> https://lists.freedesktop.org/archives/dri-devel/2016-January/098867.html
> > 
> > I like the linked patch much better, since non-atomic really should die.
> > Inflicting non-atomic on atomic helpers is bad imo, so nack from me on
> > this patch here.
> 
> I mostly agree, but we are in a transition period from non-atomic to
> atomic. When all drivers have been converted to atomic, it should be
> easy to grep for code using DRIVER_ATOMIC (or similar), and remove all
> the non-atomic support code.
> 
> In my opinion it should be considered case by case if the
> non-atomic/atomic compat code should be added to the generic functions
> or to all the drivers using that functionality.
> 
> In this case, if it only affects tda998x (but does it?), perhaps the
> patch in the link is better.

Maybe we need a hybrid helper that just calls the atomic
or non-atomic helper approppriately.

-- 
Ville Syrjälä
Intel OTC