From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Subject: Re: [PATCH v2] drm/i915: Increase WM memory latency
 values on SNB
Date: Thu, 15 May 2014 13:45:52 +0300
Message-ID: <20140515104552.GR18465@intel.com>
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To: Jani Nikula <jani.nikula@intel.com>
Cc: Robert N <crshman@gmail.com>, intel-gfx@lists.freedesktop.org, Arthur Ranyan <arthur.j.runyan@intel.com>
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On Thu, May 15, 2014 at 01:34:44PM +0300, Jani Nikula wrote:
> On Thu, 15 May 2014, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > On Thu, May 15, 2014 at 01:13:21PM +0300, Jani Nikula wrote:
> >> On Thu, 08 May 2014, ville.syrjala@linux.intel.com wrote:
> >> > From: Ville Syrj=E4l=E4 <ville.syrjala@linux.intel.com>
> >> > +static void snb_wm_latency_quirk(struct drm_device *dev)
> >> > +{
> >> > +	struct drm_i915_private *dev_priv =3D dev->dev_private;
> >> > +	bool changed;
> >> > +
> >> > +	/*
> >> > +	 * The BIOS provided WM memory latency values are often
> >> > +	 * inadequate for high resolution displays. Adjust them.
> >> > +	 */
> >> > +	changed =3D ilk_increase_wm_latency(dev_priv, dev_priv->wm.pri_lat=
ency, 12) |
> >> > +		ilk_increase_wm_latency(dev_priv, dev_priv->wm.spr_latency, 12) |
> >> > +		ilk_increase_wm_latency(dev_priv, dev_priv->wm.cur_latency, 12);
> >> =

> >> Nitpick, s/|/||/g for bools.
> >
> > Consider side effects.
> =

> Ugh I'm slow today. Some might claim business as usual. I'll hide
> somewhere.
> =

> Before I head under the rock, may I say bitops on bools are still ugly?

I tend to use them but Paulo was also confused by them somewhere else
in the watermark code, so maybe I should stop using them?

I can rewrite as:
changed |=3D ilk_increase_wm_latency(dev_priv, dev_priv->wm.pri_latency, 12=
);
changed |=3D ilk_increase_wm_latency(dev_priv, dev_priv->wm.spr_latency, 12=
);
changed |=3D ilk_increase_wm_latency(dev_priv, dev_priv->wm.cur_latency, 12=
);

or just 3x
if (ilk_increase_wm_latency(...))
	changed =3D true;

if that helps.

-- =

Ville Syrj=E4l=E4
Intel OTC