Re: [PATCH 2/2] drm/i915: Adjust sideband locking a bit for CHV/VLV

Ville Syrjälä
2015-05-27T08:06:06Z

On Wed, May 27, 2015 at 11:03:09AM +0300, Jani Nikula wrote:
> On Tue, 26 May 2015, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > chv_enable_pll() doesn't need to hold sb_lock for the entire duration of
> > the function. Drop the lock as soon as possible.
> >
> > valleyview_set_cdclk() does a potential lock+unlock+lock+unlock cycle
> > with sb_lock. Move Grab the lock a few lines earlier so we can make do
>
> Move Grab?

s/Move //

>
> Anyway, both patches are
>
> Reviewed-by: Jani Nikula <jani.nikula@intel.com>
>
>
> > with a single lock+unlock cycle always.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> > drivers/gpu/drm/i915/intel_display.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 72b6529..067b1de 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -1668,6 +1668,8 @@ static void chv_enable_pll(struct intel_crtc *crtc,
> > tmp |= DPIO_DCLKP_EN;
> > vlv_dpio_write(dev_priv, pipe, CHV_CMN_DW14(port), tmp);
> >
> > + mutex_unlock(&dev_priv->sb_lock);
> > +
> > /*
> > * Need to wait > 100ns between dclkp clock enable bit and PLL enable.
> > */
> > @@ -1683,8 +1685,6 @@ static void chv_enable_pll(struct intel_crtc *crtc,
> > /* not sure when this should be written */
> > I915_WRITE(DPLL_MD(pipe), pipe_config->dpll_hw_state.dpll_md);
> > POSTING_READ(DPLL_MD(pipe));
> > -
> > - mutex_unlock(&dev_priv->sb_lock);
> > }
> >
> > static int intel_num_dvo_pipes(struct drm_device *dev)
> > @@ -5780,12 +5780,13 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
> > }
> > mutex_unlock(&dev_priv->rps.hw_lock);
> >
> > + mutex_lock(&dev_priv->sb_lock);
> > +
> > if (cdclk == 400000) {
> > u32 divider;
> >
> > divider = DIV_ROUND_CLOSEST(dev_priv->hpll_freq << 1, cdclk) - 1;
> >
> > - mutex_lock(&dev_priv->sb_lock);
> > /* adjust cdclk divider */
> > val = vlv_cck_read(dev_priv, CCK_DISPLAY_CLOCK_CONTROL);
> > val &= ~DISPLAY_FREQUENCY_VALUES;
> > @@ -5796,10 +5797,8 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
> > DISPLAY_FREQUENCY_STATUS) == (divider << DISPLAY_FREQUENCY_STATUS_SHIFT),
> > 50))
> > DRM_ERROR("timed out waiting for CDclk change\n");
> > - mutex_unlock(&dev_priv->sb_lock);
> > }
> >
> > - mutex_lock(&dev_priv->sb_lock);
> > /* adjust self-refresh exit latency value */
> > val = vlv_bunit_read(dev_priv, BUNIT_REG_BISOC);
> > val &= ~0x7f;
> > @@ -5813,6 +5812,7 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
> > else
> > val |= 3000 / 250; /* 3.0 usec */
> > vlv_bunit_write(dev_priv, BUNIT_REG_BISOC, val);
> > +
> > mutex_unlock(&dev_priv->sb_lock);
> >
> > vlv_update_cdclk(dev);
> > --
> > 2.3.6
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Jani Nikula, Intel Open Source Technology Center

--
Ville Syrjälä
Intel OTC