linux-kernel - Re: [RFC 10/16] drm/nouveau/timer: skip calibration on GK20A

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Message-ID: <CACAvsv4T=TRb05OtkxG=t1+Ou9=Of9c-ALWkHJjKYpNi2aGs5Q@mail.gmail.com>
Date:	Tue, 4 Feb 2014 13:55:57 +1000
From:	Ben Skeggs <skeggsb@...il.com>
To:	Alexandre Courbot <acourbot@...dia.com>
Cc:	Ben Skeggs <bskeggs@...hat.com>,
	"nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Eric Brower <ebrower@...dia.com>,
	Stephen Warren <swarren@...dotorg.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	Terje Bergstrom <tbergstrom@...dia.com>,
	Ken Adams <KAdams@...dia.com>
Subject: Re: [RFC 10/16] drm/nouveau/timer: skip calibration on GK20A

On Sat, Feb 1, 2014 at 1:16 PM, Alexandre Courbot <acourbot@...dia.com> 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.
Just a curiosity:  What timer resolution does the HW initialise at?

>
> Signed-off-by: Alexandre Courbot <acourbot@...dia.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 c0bdd10..822fe0d 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;
> +
>         /* aim for 31.25MHz, which gives us nanosecond timestamps */
>         d = 1000000 / 32;
>
> @@ -235,20 +239,23 @@ nv04_timer_init(struct nouveau_object *object)
>                 d >>= 1;
>         }
>
> -       /* restore the time before suspend */
> -       lo = priv->suspend_time;
> -       hi = (priv->suspend_time >> 32);
> -
>         nv_debug(priv, "input frequency : %dHz\n", f);
>         nv_debug(priv, "input multiplier: %d\n", m);
>         nv_debug(priv, "numerator       : 0x%08x\n", n);
>         nv_debug(priv, "denominator     : 0x%08x\n", d);
>         nv_debug(priv, "timer frequency : %dHz\n", (f * m) * d / n);
> -       nv_debug(priv, "time low        : 0x%08x\n", lo);
> -       nv_debug(priv, "time high       : 0x%08x\n", hi);
>
>         nv_wr32(priv, NV04_PTIMER_NUMERATOR, n);
>         nv_wr32(priv, NV04_PTIMER_DENOMINATOR, d);
> +
> +skip_clk_init:
> +       /* restore the time before suspend */
> +       lo = priv->suspend_time;
> +       hi = (priv->suspend_time >> 32);
> +
> +       nv_debug(priv, "time low        : 0x%08x\n", lo);
> +       nv_debug(priv, "time high       : 0x%08x\n", hi);
> +
>         nv_wr32(priv, NV04_PTIMER_INTR_0, 0xffffffff);
>         nv_wr32(priv, NV04_PTIMER_INTR_EN_0, 0x00000000);
>         nv_wr32(priv, NV04_PTIMER_TIME_1, hi);
> --
> 1.8.5.3
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
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