[Intel-gfx] [PATCH] drm/i915: Remove the disabling of VHR unit clock gating for HSW

[Paulo Zanoni]

2012/10/5 Damien Lespiau <damien.lespiau at gmail.com>:
> From: Damien Lespiau <damien.lespiau at intel.com>
>
> There's is another register (a read only, so no harm done) at 0x42020 on
> Haswell GPUs. Let's just remove the write from the copy&paste that
> introduced haswell_init_clock_gating().
>
> A note for the interested reader, it does seem we have a duplication of
> the 0x42020 register definition, hence the removal of 2 writes. That
> duplication could be the object of a later patch.
>
> Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>

Nice catch!

As you pointed, it seems that we're applying the same workaround twice
in some functions. You fixed the problem in haswell_init_clock_gating
by just removing both register writes, but could you also write a new
patch to fix ivybridge_init_clock_gating and
valleyview_init_clock_gating to not apply the same workaround twice?
Maybe just remove the ILK_DSPCLK_GATE definitions and just use
PCH_DSPCLK_GATE_D everywhere, removing duplicated code? Then we'd also
have to check ironlake_init_clock_gating and gen6_init_clock_gating...

Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

(patch "drm/i915: Remove the WaDisableBackToBackFlipFix w/a for
Haswell" also got a tested-by now btw...)

> ---
>  drivers/gpu/drm/i915/intel_pm.c |    5 -----
>  1 files changed, 0 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index d0403e8..eb757e5 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3460,9 +3460,6 @@ static void haswell_init_clock_gating(struct drm_device *dev)
>  {
>         struct drm_i915_private *dev_priv = dev->dev_private;
>         int pipe;
> -       uint32_t dspclk_gate = VRHUNIT_CLOCK_GATE_DISABLE;
> -
> -       I915_WRITE(PCH_DSPCLK_GATE_D, dspclk_gate);
>
>         I915_WRITE(WM3_LP_ILK, 0);
>         I915_WRITE(WM2_LP_ILK, 0);
> @@ -3473,8 +3470,6 @@ static void haswell_init_clock_gating(struct drm_device *dev)
>          */
>         I915_WRITE(GEN6_UCGCTL2, GEN6_RCZUNIT_CLOCK_GATE_DISABLE);
>
> -       I915_WRITE(ILK_DSPCLK_GATE, IVB_VRHUNIT_CLK_GATE);
> -
>         /* WaDisableEarlyCull */
>         I915_WRITE(_3D_CHICKEN3,
>                    _MASKED_BIT_ENABLE(_3D_CHICKEN_SF_DISABLE_OBJEND_CULL));
> --
> 1.7.7.5
>
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-- 
Paulo Zanoni