[Intel-gfx] [PATCH] drm/i915: don't double-restore ARB mode bits for kms

[Paulo Zanoni]

2014/1/16 Daniel Vetter <daniel.vetter at ffwll.ch>:
> Our init_clock_gating functions and related code should already take
> care of this. And if they don't we'd better know.

For both registers, I see functions applying specific workarounds, but
they only do the read-write-modify through _MASKED_BIT_ENABLE(). I
don't see anybody explicitly fully initializing the registers
anywhere. So we go with whatever the BIOS gives us at boot + our
changes to a few specific registers. At resume, we don't know so far
what we'll get, so I fear this patch may in fact cause a regression.


>
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> ---
>  drivers/gpu/drm/i915/i915_suspend.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
> index e6c90d1382b3..0b72fcd28d4d 100644
> --- a/drivers/gpu/drm/i915/i915_suspend.c
> +++ b/drivers/gpu/drm/i915/i915_suspend.c
> @@ -348,12 +348,14 @@ int i915_save_state(struct drm_device *dev)
>
>         intel_disable_gt_powersave(dev);
>
> -       /* Cache mode state */
> -       if (INTEL_INFO(dev)->gen < 7)
> -               dev_priv->regfile.saveCACHE_MODE_0 = I915_READ(CACHE_MODE_0);
> +       if (!drm_core_check_feature(dev, DRIVER_MODESET)) {
> +               /* Cache mode state */
> +               if (INTEL_INFO(dev)->gen < 7)
> +                       dev_priv->regfile.saveCACHE_MODE_0 = I915_READ(CACHE_MODE_0);
>
> -       /* Memory Arbitration state */
> -       dev_priv->regfile.saveMI_ARB_STATE = I915_READ(MI_ARB_STATE);
> +               /* Memory Arbitration state */
> +               dev_priv->regfile.saveMI_ARB_STATE = I915_READ(MI_ARB_STATE);
> +       }
>
>         /* Scratch space */
>         for (i = 0; i < 16; i++) {
> @@ -394,13 +396,15 @@ int i915_restore_state(struct drm_device *dev)
>                 }
>         }
>
> -       /* Cache mode state */
> -       if (INTEL_INFO(dev)->gen < 7)
> -               I915_WRITE(CACHE_MODE_0, dev_priv->regfile.saveCACHE_MODE_0 |
> -                          0xffff0000);
> +       if (!drm_core_check_feature(dev, DRIVER_MODESET)) {
> +               /* Cache mode state */
> +               if (INTEL_INFO(dev)->gen < 7)
> +                       I915_WRITE(CACHE_MODE_0, dev_priv->regfile.saveCACHE_MODE_0 |
> +                                  0xffff0000);
>
> -       /* Memory arbitration state */
> -       I915_WRITE(MI_ARB_STATE, dev_priv->regfile.saveMI_ARB_STATE | 0xffff0000);
> +               /* Memory arbitration state */
> +               I915_WRITE(MI_ARB_STATE, dev_priv->regfile.saveMI_ARB_STATE | 0xffff0000);
> +       }
>
>         for (i = 0; i < 16; i++) {
>                 I915_WRITE(SWF00 + (i << 2), dev_priv->regfile.saveSWF0[i]);
> --
> 1.8.5.2
>
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-- 
Paulo Zanoni