[Intel-gfx] [PATCH 1/6] drm/i915: Warn if a pipe is enabled with a bogus port

[Paulo Zanoni]

Hi

2013/3/7 Damien Lespiau <damien.lespiau at intel.com>:
> If TRANS_DDI_FUNC_CTL has been wrongly programmed with an incorrect
> port, we are currently trying to read PORT_CLK_SEL(port) with an
> initialized value.

s/initialized/uninitialized/g

>
> Handle that case by returning PORT_CLK_SEL_NONE and warning about it.
>
> Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
>
> to add to first

First!

> ---
>  drivers/gpu/drm/i915/intel_ddi.c |   11 +++++++++--
>  1 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index 56bb7cb..3b5838d 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -1157,7 +1157,7 @@ static uint32_t intel_ddi_get_crtc_pll(struct drm_i915_private *dev_priv,
>                                        enum pipe pipe)
>  {
>         uint32_t temp, ret;
> -       enum port port;
> +       enum port port = I915_MAX_PORTS;
>         enum transcoder cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv,
>                                                                       pipe);
>         int i;
> @@ -1173,7 +1173,10 @@ static uint32_t intel_ddi_get_crtc_pll(struct drm_i915_private *dev_priv,
>                                 port = i;
>         }
>
> -       ret = I915_READ(PORT_CLK_SEL(port));
> +       if (port == I915_MAX_PORTS)
> +               ret = PORT_CLK_SEL_NONE;

I would put the WARN here (see below).

> +       else
> +               ret = I915_READ(PORT_CLK_SEL(port));
>
>         DRM_DEBUG_KMS("Pipe %c connected to port %c using clock 0x%08x\n",
>                       pipe_name(pipe), port_name(port), ret);
> @@ -1207,6 +1210,10 @@ void intel_ddi_setup_hw_pll_state(struct drm_device *dev)
>                 case PORT_CLK_SEL_WRPLL2:
>                         dev_priv->ddi_plls.wrpll2_refcount++;
>                         break;
> +               case PORT_CLK_SEL_NONE:
> +                       WARN(1, "Pipe %c enabled but no clock selected\n",
> +                            pipe_name(pipe));

I would put this WARN inside intel_ddi_get_crtc_pll, because that's
the function that really detects the "problem". Currently the function
has only 1 caller, but this could change in the future, and other
callers should also get their WARNs.


> +                       break;
>                 }
>         }
>  }
> --
> 1.7.7.5
>
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-- 
Paulo Zanoni