Re: [PATCH 5/6] drm/i915: BDW needs D_COMP writes through MCHBAR

Imre Deak
2014-04-01T15:53:28Z

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On Fri, 2014-03-07 at 20:12 -0300, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
>
> That's what the spec said! And HSW needs it through pcode (you can
> only read it through MCHBAR), so create hsw_write_dcomp to abstract
> the weirdness.
>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
> drivers/gpu/drm/i915/intel_display.c | 28 ++++++++++++++++++----------
> 1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index d6092be..2be4129 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6664,6 +6664,22 @@ static void assert_can_disable_lcpll(struct drm_i915_private *dev_priv)
> spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
> }
>
> +static void hsw_write_dcomp(struct drm_i915_private *dev_priv, uint32_t val)
> +{
> + struct drm_device *dev = dev_priv->dev;
> +
> + if (IS_HASWELL(dev)) {
> + mutex_lock(&dev_priv->rps.hw_lock);
> + if (sandybridge_pcode_write(dev_priv, GEN6_PCODE_WRITE_D_COMP,
> + val))
> + DRM_ERROR("Failed to disable D_COMP\n");
> + mutex_unlock(&dev_priv->rps.hw_lock);
> + } else {
> + I915_WRITE(D_COMP, val);
> + }
> + POSTING_READ(D_COMP);
> +}
> +
> /*
> * This function implements pieces of two sequences from BSpec:
> * - Sequence for display software to disable LCPLL
> @@ -6701,11 +6717,7 @@ static void hsw_disable_lcpll(struct drm_i915_private *dev_priv,
>
> val = I915_READ(D_COMP);
> val |= D_COMP_COMP_DISABLE;
> - mutex_lock(&dev_priv->rps.hw_lock);
> - if (sandybridge_pcode_write(dev_priv, GEN6_PCODE_WRITE_D_COMP, val))
> - DRM_ERROR("Failed to disable D_COMP\n");
> - mutex_unlock(&dev_priv->rps.hw_lock);
> - POSTING_READ(D_COMP);
> + hsw_write_dcomp(dev_priv, val);
> ndelay(100);
>
> if (wait_for((I915_READ(D_COMP) & D_COMP_RCOMP_IN_PROGRESS) == 0, 1))
> @@ -6760,11 +6772,7 @@ static void hsw_restore_lcpll(struct drm_i915_private *dev_priv)
> val = I915_READ(D_COMP);
> val |= D_COMP_COMP_FORCE;
> val &= ~D_COMP_COMP_DISABLE;
> - mutex_lock(&dev_priv->rps.hw_lock);
> - if (sandybridge_pcode_write(dev_priv, GEN6_PCODE_WRITE_D_COMP, val))
> - DRM_ERROR("Failed to enable D_COMP\n");
> - mutex_unlock(&dev_priv->rps.hw_lock);
> - POSTING_READ(D_COMP);
> + hsw_write_dcomp(dev_priv, val);
>
> val = I915_READ(LCPLL_CTL);
> val &= ~LCPLL_PLL_DISABLE;

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