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List:       linux-tegra
Subject:    Re: [PATCH 02/12] drm/nouveau/timer: skip calibration on GK20A
From:       Ben Skeggs <skeggsb () gmail ! com>
Date:       2014-03-26 4:19:49
Message-ID: CACAvsv54BF3cD6y59=kQ=1j-S9tGixTz_J3gx2mbOEkB2eQ4cA () mail ! gmail ! com
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On Tue, Mar 25, 2014 at 7:54 AM, Thierry Reding
<thierry.reding@gmail.com> wrote:
> On Mon, Mar 24, 2014 at 05:42:24PM +0900, Alexandre Courbot wrote:
> > GK20A's timer is directly attached to the system timer and cannot be
> > calibrated. Skip the calibration phase on that chip since the
> > corresponding registers do not exist.
> > 
> > Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> > ---
> > drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c | 19 +++++++++++++------
> > 1 file changed, 13 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c \
> > b/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c index \
> >                 c0bdd10358d7..822fe0d8a871 100644
> > --- a/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c
> > +++ b/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c
> > @@ -185,6 +185,10 @@ nv04_timer_init(struct nouveau_object *object)
> > if (ret)
> > return ret;
> > 
> > +     /* gk20a does not have the calibration registers */
> > +     if (device->chipset == 0xea)
> > +             goto skip_clk_init;
> 
> I'm concerned that this won't scale in the future. Perhaps a better
> solution would be to add a "flags" or "features" field to struct
> nouveau_device along with feature bits such as HAS_CALIBRATION or
> similar.
> 
> That way we don't have to touch this code for every new future Tegra
> chip. Unless perhaps if there's a reason to expect things to change in
> newer generations.
I've already handled this in a slightly different way in the tree I'd
previously pointed Alex at (I think!), as I needed to do the same for
GM107.

Should just be able to use that implementation (so, just change the
probe patch) here too.

Thanks,
Ben.

> 
> Thierry
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
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