Re: [PATCH 08/10] drm/i915: don't rely on previous values set on DDI_BUF_CTL

Daniel Vetter
2012-10-10T18:17:22Z

On Wed, Oct 10, 2012 at 04:56:07PM +0200, Daniel Vetter wrote:
> On Wed, Oct 10, 2012 at 03:27:59PM +0100, Lespiau, Damien wrote:
> > On Fri, Oct 5, 2012 at 4:05 PM, Paulo Zanoni <przanoni@gmail.com> wrote:
> > > From: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > >
> > > Just set the only bit we need, everything else is either ignored on
> > > HDMI or should be set to zero.
> > >
> > > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> >
> > Is the assumption that intel_enable_ddi() will only ever be used by
> > the HDMI encore likely to hold true for ever? looks like a general
> > function that could be used by others to me. Also intel_disable_ddi()
> > read the register back, so it'd be unfair to only touch
> > intel_enable_ddi() if you want to do that.
> >
> > I'd just stay on the safe side and retain the programming here.
>
> I'd prefer to go safe and do our own programming ;-) Imo it's better to
> fully program a register than to rely on random garbage left behind by the
> bios - usually that allows us to bring up hw a bit quicker, but in the end
> results in some nasty bug reports once hw starts shipping. For the disable
> side things are usually not that important, since we need to assume that
> our own code (or our own hw state readout) set things up correctly.
>
> Wrt the general usefullness of, I guess the dp patches will changed that.
> I'll just merge this one here.

Ok, I've merged this series up to this patch. The last two patches are
pending an r-b from a volunteer ;-)

Thanks, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch