[Intel-gfx] [PATCH v2] drm/i915: Don't enable IPS when pixel rate exceeds 95% of cdclk

[Jani Nikula]

On Fri, 12 Sep 2014, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> On Fri, Sep 12, 2014 at 04:42:33PM +0100, Chris Wilson wrote:
>> On Fri, Sep 12, 2014 at 05:01:57PM +0300, ville.syrjala at linux.intel.com wrote:
>> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> > 
>> > Bspec says we shouldn't enable IPS on BDW when the pipe pixel rate
>> > exceeds 95% of the core display clock. Apparently this can cause
>> > underruns.
>> > 
>> > There's no similar restriction listed for HSW, so leave that one alone
>> > for now.
>> > 
>> > v2: Add pipe_config_supports_ips() (Chris)
>> > 
>> > Tested-by: Timo Aaltonen <tjaalton at ubuntu.com>
>> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83497
>> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> > ---
>> >  drivers/gpu/drm/i915/intel_display.c | 21 +++++++++++++++++++--
>> >  drivers/gpu/drm/i915/intel_drv.h     |  1 +
>> >  drivers/gpu/drm/i915/intel_pm.c      | 16 +++++++---------
>> >  3 files changed, 27 insertions(+), 11 deletions(-)
>> > 
>> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> > index 965eb3c..7809177 100644
>> > --- a/drivers/gpu/drm/i915/intel_display.c
>> > +++ b/drivers/gpu/drm/i915/intel_display.c
>> > @@ -5241,12 +5241,29 @@ retry:
>> >  	return setup_ok ? 0 : -EINVAL;
>> >  }
>> >  
>> > +static bool pipe_config_supports_ips(struct drm_i915_private *dev_priv,
>> > +				     struct intel_crtc_config *pipe_config)
>> > +{
>> > +	if (pipe_config->pipe_bpp > 24)
>> > +		return false;
>> > +
>> > +	/* HSW can handle pixel rate up to cdclk? */
>> > +	if (IS_HASWELL(dev_priv->dev))
>> 
>> This only needs IS_HASWELL(dev_priv)
>
> old habits...

Thanks to your old habits I didn't have to make any changes when pushing
this to drm-intel-fixes which is still old habit land. Thanks for the
patch and review.

BR,
Jani.


>
>> 
>> > +		return true;
>> > +
>> > +	return ilk_pipe_pixel_rate(pipe_config) <=
>> > +		intel_ddi_get_cdclk_freq(dev_priv) * 95 / 100;
>> 
>> Otherwise
>> Acked-by: Chris Wilson <chris at chris-wilson.co.uk>
>> -Chris
>> 
>> -- 
>> Chris Wilson, Intel Open Source Technology Centre
>
> -- 
> Ville Syrjälä
> Intel OTC
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-- 
Jani Nikula, Intel Open Source Technology Center