Re: [PATCH] drm/i915: Disable MI_STORE_DATA_IMM for i915g/i915gm

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Sep 06, 2017 at 03:40:08PM +0100, Chris Wilson wrote:
> The early gen3 machines (i915g/Grantsdale and i915gm/Alviso) share a lot
> of characteristics in their MI/GTT blocks with gen2, and in particular
> can only use physical addresses in MI_STORE_DATA_IMM. This makes it
> incompatible with our usage, so include those two machines in the
> blacklist to prevent usage.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_drv.h            |  7 -------
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |  7 ++++---
>  drivers/gpu/drm/i915/intel_engine_cs.c     | 16 ++++++++++++++++
>  drivers/gpu/drm/i915/intel_ringbuffer.h    | 12 +-----------
>  4 files changed, 21 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 789f7502cd1f..6020a94daf81 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -4360,11 +4360,4 @@ int remap_io_mapping(struct vm_area_struct *vma,
>  		     unsigned long addr, unsigned long pfn, unsigned long size,
>  		     struct io_mapping *iomap);
>  
> -static inline bool
> -intel_engine_can_store_dword(struct intel_engine_cs *engine)
> -{
> -	return __intel_engine_can_store_dword(INTEL_GEN(engine->i915),
> -					      engine->class);
> -}
> -
>  #endif
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 53718a245ded..7687483ff218 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1168,6 +1168,9 @@ static u32 *reloc_gpu(struct i915_execbuffer *eb,
>  		if (eb_use_cmdparser(eb))
>  			return ERR_PTR(-EWOULDBLOCK);
>  
> +		if (!intel_engine_can_store_dword(eb->engine))
> +			return ERR_PTR(-ENODEV);
> +
>  		err = __reloc_gpu_alloc(eb, vma, len);
>  		if (unlikely(err))
>  			return ERR_PTR(err);
> @@ -1192,9 +1195,7 @@ relocate_entry(struct i915_vma *vma,
>  
>  	if (!eb->reloc_cache.vaddr &&
>  	    (DBG_FORCE_RELOC == FORCE_GPU_RELOC ||
> -	     !reservation_object_test_signaled_rcu(vma->resv, true)) &&
> -	    __intel_engine_can_store_dword(eb->reloc_cache.gen,
> -					   eb->engine->class)) {
> +	     !reservation_object_test_signaled_rcu(vma->resv, true))) {
>  		const unsigned int gen = eb->reloc_cache.gen;
>  		unsigned int len;
>  		u32 *batch;
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index ae668340620e..ff56de4816cb 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1378,6 +1378,22 @@ void intel_engines_mark_idle(struct drm_i915_private *i915)
>  	}
>  }
>  
> +bool intel_engine_can_store_dword(struct intel_engine_cs *engine)
> +{
> +	int gen = INTEL_GEN(engine->i915);
> +
> +	if (gen <= 2)
> +		return false; /* uses physical not virtual addresses */
> +
> +	if (gen == 3 && (IS_I915G(engine->i915) || IS_I915GM(engine->i915)))
> +		return false; /* uses physical not virtual addresses */

nit: 'gen' check seems redundant.

I suppose trying to do the relocs using physical addresses would be
quite a bit of work for little gain.

Patch lgtm
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
> +	if (gen == 6 && engine->class == VIDEO_DECODE_CLASS)
> +		return false; /* b0rked */
> +
> +	return true;
> +}
> +
>  #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>  #include "selftests/mock_engine.c"
>  #endif
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 02d8974bf9ab..79c0021f3700 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -735,16 +735,6 @@ bool intel_engines_are_idle(struct drm_i915_private *dev_priv);
>  void intel_engines_mark_idle(struct drm_i915_private *i915);
>  void intel_engines_reset_default_submission(struct drm_i915_private *i915);
>  
> -static inline bool
> -__intel_engine_can_store_dword(unsigned int gen, unsigned int class)
> -{
> -	if (gen <= 2)
> -		return false; /* uses physical not virtual addresses */
> -
> -	if (gen == 6 && class == VIDEO_DECODE_CLASS)
> -		return false; /* b0rked */
> -
> -	return true;
> -}
> +bool intel_engine_can_store_dword(struct intel_engine_cs *engine);
>  
>  #endif /* _INTEL_RINGBUFFER_H_ */
> -- 
> 2.14.1
> 
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-- 
Ville Syrjälä
Intel OTC
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