Re: [PATCH 18/49] drm/i915/bxt: add workaround to avoid PTE corruption

Daniel Vetter
2015-03-17T10:35:07Z

On Tue, Mar 17, 2015 at 11:39:44AM +0200, Imre Deak wrote:
> From: Robert Beckett <robert.beckett@intel.com>
>
> Set TLBPF in TILECTL. This fixes an issue with BXT HW seeing
> corrupted pte entries.

Is this for the ggtt or ppgtt ptes?
-Daniel

>
> v2:
> - move the workaround to bxt_init_clock_gating (imre)
>
> Signed-off-by: Robert Beckett <robert.beckett@intel.com> (v1)
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/intel_pm.c | 2 ++
> 2 files changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 1d074e8..d69d7b9 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1151,6 +1151,7 @@ enum skl_disp_power_wells {
> /* control register for cpu gtt access */
> #define TILECTL 0x101000
> #define TILECTL_SWZCTL (1 << 0)
> +#define TILECTL_TLBPF (1 << 1)
> #define TILECTL_TLB_PREFETCH_DIS (1 << 2)
> #define TILECTL_BACKSNOOP_DIS (1 << 3)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 52d3c02..d3f2557 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -110,6 +110,8 @@ static void bxt_init_clock_gating(struct drm_device *dev)
> GEN8_SDEUNIT_CLOCK_GATE_DISABLE |
> GEN8_HDCUNIT_CLOCK_GATE_DISABLE_HDCREQ);
>
> + /* FIXME: apply on A0 only */
> + I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_TLBPF);
> }
>
> static void i915_pineview_get_mem_freq(struct drm_device *dev)
> --
> 2.1.0
>
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--
Daniel Vetter
Software Engineer, Intel Corporation