Re: [PATCH 09/18] drm/i915: Add functions to allocate / release gem obj for GuC

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Mar 26, 2015 at 12:41:16PM -0700, yu.dai@intel.com wrote:
> From: Alex Dai <yu.dai@intel.com>
> 
> All gem objects used by GuC are pinned to ggtt space out of range
> [0, WOPCM size]. In GuC address space mapping, [0, WPOCM size] is
> used internally for its Boot ROM, SRAM etc. Currently this WPOCM
> size is 512K. This is done by using of PIN_OFFSET_BIAS.
> 
> Issue: VIZ-4884
> Signed-off-by: Alex Dai <yu.dai@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_guc.h        |  3 +++
>  drivers/gpu/drm/i915/intel_guc_loader.c | 34 +++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
> index d8262cf..ae14c57 100644
> --- a/drivers/gpu/drm/i915/intel_guc.h
> +++ b/drivers/gpu/drm/i915/intel_guc.h
> @@ -92,5 +92,8 @@ struct intel_guc {
>  extern int intel_guc_load_ucode(struct drm_device *dev, bool wait);
>  extern void intel_guc_ucode_fini(struct drm_device *dev);
>  extern void intel_guc_ucode_init(struct drm_device *dev);
> +struct drm_i915_gem_object *
> +intel_guc_allocate_gem_obj(struct drm_device *dev, u32 size);
> +void intel_guc_release_gem_obj(struct drm_i915_gem_object *obj);
>  
>  #endif
> diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
> index 315e5d9..0500a53 100644
> --- a/drivers/gpu/drm/i915/intel_guc_loader.c
> +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
> @@ -30,6 +30,40 @@
>  MODULE_FIRMWARE(I915_GUC_UCODE_GEN8);
>  MODULE_FIRMWARE(I915_GUC_UCODE_GEN9);
>  
> +struct drm_i915_gem_object *
> +intel_guc_allocate_gem_obj(struct drm_device *dev, u32 size)
> +{
> +	struct drm_i915_gem_object *obj;
> +
> +	obj = i915_gem_alloc_object(dev, size);
> +	if (!obj)
> +		return NULL;
> +
> +	if (i915_gem_object_get_pages(obj)) {
> +		drm_gem_object_unreference(&obj->base);
> +		return NULL;
> +	}
> +
> +	if (i915_gem_obj_ggtt_pin(obj, PAGE_SIZE,
> +			PIN_OFFSET_BIAS | GUC_WOPCM_SIZE_VALUE)) {

Please add a comment here about how much pin bias you exactly need and
why. Otherwise this will be extremely arcane knowledge lost when someone
reworks the pin bias stuff or changes the default offset.

Or well just use the right offset directly, since atm PIN_OFFSET_BIAS is
256k and you claim to need 512k.
-Daniel

> +		drm_gem_object_unreference(&obj->base);
> +		return NULL;
> +	}
> +
> +	return obj;
> +}
> +
> +void intel_guc_release_gem_obj(struct drm_i915_gem_object *obj)
> +{
> +	if (!obj)
> +		return;
> +
> +	if (i915_gem_obj_is_pinned(obj))
> +		i915_gem_object_ggtt_unpin(obj);
> +
> +	drm_gem_object_unreference(&obj->base);
> +}
> +
>  static int copy_rsa(struct drm_i915_private *dev_priv)
>  {
>  	struct sg_table *st = dev_priv->guc.guc_fw.uc_fw_obj->pages;
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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