Re: [PATCH] drm/i915/psr: simplify enable_psr handling

[Daniel Vetter]

On Fri, Dec 21, 2018 at 8:53 PM Ross Zwisler <zwisler@xxxxxxxxxx> wrote:
>
> On Fri, Dec 21, 2018 at 11:23:07AM -0800, Dhinakaran Pandiyan wrote:
> > On Fri, 2018-12-21 at 10:23 -0700, Ross Zwisler wrote:
> > > The following commit:
> > >
> > > commit 2bdd045e3a30 ("drm/i915/psr: Check if VBT says PSR can be
> > > enabled.")
> > >
> > > added some code with no usable functionality.  Regardless of how the
> > > psr
> > > default is set up in the BDB_DRIVER_FEATURES section, if the
> > > enable_psr
> > > module parameter isn't specified it defaults to 0.
> > Right, that was intentional and the commit message even makes a note of
> > it
> > " Note: The feature currently remains disabled by default for all
> > platforms irrespective of what VBT says."
> >
> >
> > Anyway, we've enabled the feature by default now and the current code
> > should take into account the VBT flag if the module parameter is left
> > to a default value. Please check git://anongit.freedesktop.org/drm-tip
> > drm-tip.
>
> Fair enough.  It's a bad pattern to introduce dead code as a placeholder for
> some future work, though.  This code has been in the tree for three major
> kernel releases (v4.{18,19,20}) without providing any useful functionality.

Getting PSR enabled by default on at least a few platforms took years.
Insisting that we do not ever merge such code also doesn't work.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch