Re: [PATCH] drm/i915/vlv: add VLV specific clock_get function v3

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Sep 25, 2013 at 10:38:33AM -0700, Jesse Barnes wrote:
> On Mon, 23 Sep 2013 21:01:44 +0300
> Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> 
> > On Fri, Sep 20, 2013 at 11:29:32AM -0700, Jesse Barnes wrote:
> > > Calculation is a little different than other platforms.
> > > 
> > > v2: update to use port_clock instead
> > >     rebase on top of Ville's changes
> > > v3: update to new port_clock semantics - don't divide by
> > >     pixel_multiplier (Ville)
> > > 
> > > References: https://bugs.freedesktop.org/show_bug.cgi?id=67345
> > > Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > ---
> > >  drivers/gpu/drm/i915/intel_display.c |   33 ++++++++++++++++++++++++++++++++-
> > >  1 file changed, 32 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 7eecf37..e5c9c1c 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -5048,6 +5048,34 @@ static void i9xx_get_pfit_config(struct intel_crtc *crtc,
> > >  			I915_READ(LVDS) & LVDS_BORDER_ENABLE;
> > >  }
> > >  
> > > +static void vlv_crtc_clock_get(struct intel_crtc *crtc,
> > > +			       struct intel_crtc_config *pipe_config)
> > > +{
> > > +	struct drm_device *dev = crtc->base.dev;
> > > +	struct drm_i915_private *dev_priv = dev->dev_private;
> > > +	int pipe = pipe_config->cpu_transcoder;
> > > +	intel_clock_t clock;
> > > +	u32 mdiv;
> > > +	int refclk = 100000, fastclk, update_rate;
> > > +
> > > +	mutex_lock(&dev_priv->dpio_lock);
> > > +	mdiv = vlv_dpio_read(dev_priv, pipe, DPIO_DIV(pipe));
> > > +	mutex_unlock(&dev_priv->dpio_lock);
> > > +
> > > +	clock.m1 = (mdiv >> DPIO_M1DIV_SHIFT) & 7;
> > > +	clock.m2 = mdiv & DPIO_M2DIV_MASK;
> > > +	clock.n = (mdiv >> DPIO_N_SHIFT) & 0xf;
> > > +	clock.p1 = (mdiv >> DPIO_P1_SHIFT) & 7;
> > > +	clock.p2 = (mdiv >> DPIO_P2_SHIFT) & 0x1f;
> > > +
> > > +	update_rate = refclk / clock.n;
> > > +	clock.vco = update_rate * clock.m1 * clock.m2;
> > > +	fastclk = clock.vco / clock.p1 / clock.p2;
> > > +	clock.dot = (2 * fastclk);
> > > +
> > > +	pipe_config->port_clock = clock.dot / 10;
> > 
> > Looks like it should get roughly the right answer, but I don't see much
> > point in all the intermediate results.
> > 
> > If you want to keep some of them for clarity, then I think this should
> > be enough:
> > 
> > clock.vco = refclk * clock.m / clock.n;
> > clock.dot = clock.vco / clock.p; /* fast clock */
> > pipe_config->port_clock = clock.dot / 5;
> > 
> > Although calling the fast clock "dot" is a bit wrong, but I think it's
> > fine here, especially as it matches what I have in mind for
> > vlv_find_best_dpll(). I had to rewrite that sucker a bit to make it
> > compatible with my brain ;) I'll send a patch for that ASAP.
> 
> The other advantage of having it all spelled out like this is that it
> matches the freq calculation spreadsheet I sourced it from.
> 
> So I'd prefer to keep this as is, if I can have your r-b anyway. :)

Queued for -next with Ville's irc-r-b, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch