On Wed, Dec 21, 2016 at 02:11:26PM +0000, Chris Wilson wrote:
> The GuC would like to own the upper portion of the GTT for itself, so
> exclude it from our drm_mm to prevent us using it.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> Cc: Arkadiusz Hiler <arkadiusz.hiler@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 5 +++++
> drivers/gpu/drm/i915/intel_guc_fwif.h | 3 +++
> 2 files changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 6af9311f72f5..96bc0e83286a 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -3176,6 +3176,11 @@ int i915_ggtt_probe_hw(struct drm_i915_private *dev_priv)
> if (ret)
> return ret;
>
> + if (HAS_GUC_SCHED(dev_priv)) {
Btw, shouldn't we also modify HAS_GUC_SCHED macro to look at i915.enable_guc_submission
instead of .has_guc ? Note that Guc may be present but disabled...
> + ggtt->base.total -= GUC_GGTT_RESERVED_TOP;
Hmm, while unlikely, what if RESERVED_TOP is larger than detected base.total ?
> + ggtt->mappable_end = min(ggtt->mappable_end, ggtt->base.total);
> + }
> +
> if ((ggtt->base.total - 1) >> 32) {
> DRM_ERROR("We never expected a Global GTT with more than 32bits"
> " of address space! Found %lldM!\n",
> diff --git a/drivers/gpu/drm/i915/intel_guc_fwif.h b/drivers/gpu/drm/i915/intel_guc_fwif.h
> index 3202b32b5638..3361d38ed859 100644
> --- a/drivers/gpu/drm/i915/intel_guc_fwif.h
> +++ b/drivers/gpu/drm/i915/intel_guc_fwif.h
> @@ -23,6 +23,9 @@
> #ifndef _INTEL_GUC_FWIF_H
> #define _INTEL_GUC_FWIF_H
>
> +/* A small region at the top of the global GTT is reserved for use by the GuC */
> +#define GUC_GGTT_RESERVED_TOP 0x1200000
Is this region size fixed (part of Guc HW assumptions), or it can change per different FW?
If former, then maybe this macro should be moved to i915_guc_reg.h?
If latter, then maybe it is worth to explictly state that in the comment?
> +
> #define GFXCORE_FAMILY_GEN9 12
> #define GFXCORE_FAMILY_UNKNOWN 0x7fffffff
>
> --
> 2.11.0
>
Thanks,
Michal
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