Re: intel_pre_enable_dp

[Andi Kleen <andi@firstfloor.org>]

On Mon, Sep 30, 2013 at 01:48:13AM +0200, Andi Kleen wrote:
> 
> Jesse,
> 
> I was playing with a static analyzer and it flagged the following
> code of yours.
> 
> Is the val = 0 directly after the register read correct and intended?

Also the same pattern is in other places, like vlv_pre_enable_dp.

-Andi

> 
> commit 89b667f86a62a99a7b484a7e1b3f8f7a108a7dee
> Author: Jesse Barnes <jbarnes@virtuousgeek.org>
> Date:   Thu Apr 18 14:51:36 2013 -0700
> 
>     drm/i915: update VLV PLL and DPIO code v11
> ...
> 
>  static void intel_pre_enable_dp(struct intel_encoder *encoder)
>  {
>         struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
>         struct drm_device *dev = encoder->base.dev;
> +       struct drm_i915_private *dev_priv = dev->dev_private;
>  
>         if (is_cpu_edp(intel_dp) && !IS_VALLEYVIEW(dev))
>                 ironlake_edp_pll_on(intel_dp);
> +
> +       if (IS_VALLEYVIEW(dev)) {
> +               struct intel_digital_port *dport = enc_to_dig_port(&encoder->base);
> +               struct intel_crtc *intel_crtc =
> +                       to_intel_crtc(encoder->base.crtc);
> +               int port = vlv_dport_to_channel(dport);
> +               int pipe = intel_crtc->pipe;
> +               u32 val;
> +
> +               WARN_ON(!mutex_is_locked(&dev_priv->dpio_lock));
> +
> +               val = intel_dpio_read(dev_priv, DPIO_DATA_LANE_A(port));
> +               val = 0;      <------------- val is directly overriden, previous value is ignored
> +               if (pipe)
> +                       val |= (1<<21);
> +               else
> +                       val &= ~(1<<21);
> 
> 
> 
> 
> 
> -- 
> ak@linux.intel.com -- Speaking for myself only.

-- 
ak@linux.intel.com -- Speaking for myself only.