[Intel-gfx] [PATCH v9 08/10] drm/i915: Introduce execlist context status change notification

[Wang, Zhi A]

> -----Original Message-----
> From: Joonas Lahtinen [mailto:joonas.lahtinen at linux.intel.com]
> Sent: Thursday, June 09, 2016 1:45 PM
> To: Wang, Zhi A <zhi.a.wang at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: chris at chris-wilson.co.uk; Lv, Zhiyuan <zhiyuan.lv at intel.com>; Tian, Kevin
> <kevin.tian at intel.com>; tvrtko.ursulin at linux.intel.com
> Subject: Re: [PATCH v9 08/10] drm/i915: Introduce execlist context status
> change notification
> 
> On to, 2016-06-09 at 03:34 -0400, Zhi Wang wrote:
> > This patch introduces an approach to track the execlist context status
> > change.
> >
> > GVT-g uses GVT context as the "shadow context". The content inside GVT
> > context will be copied back to guest after the context is idle. And
> > GVT-g has to know the status of the execlist context.
> >
> > This function is configurable when creating a new GEM context.
> > Currently, Only GVT-g will create the "status-change-notification"
> > enabled GEM context.
> >
> > v8:
> >
> > - Remove the boolean flag in struct i915_gem_context. (Joonas)
> >
> > v7:
> >
> > - Remove per-engine ctx status notifiers. Use one status notifier for
> > all engines. (Joonas)
> > - Add prefix "INTEL_" for related definitions. (Joonas)
> > - Refine the comments in execlists_context_status_change(). (Joonas)
> >
> > v6:
> >
> > - When !CONFIG_DRM_I915_GVT, make GVT code as dead code then
> compiler
> > could automatically eliminate them for us. (Chris)
> > - Always initialize the notifier header, so it could be switched
> > on/off at runtime. (Chris)
> >
> > v5:
> >
> > - Only compile this feature when CONFIG_DRM_I915_GVT is
> > enabled.(Tvrtko)
> >
> > Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> > Signed-off-by: Zhi Wang <zhi.a.wang at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h         |  1 +
> >  drivers/gpu/drm/i915/i915_gem_context.c |  1 +
> >  drivers/gpu/drm/i915/intel_lrc.c        | 22 ++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_lrc.h        |  5 +++++
> >  4 files changed, 29 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > b/drivers/gpu/drm/i915/i915_drv.h index a9e22200..c14eb56 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -880,6 +880,7 @@ struct i915_gem_context {
> >  	} engine[I915_NUM_ENGINES];
> >  	u32 ring_size;
> >  	u32 desc_template;
> > +	struct atomic_notifier_head status_notifier;
> >
> >  	struct list_head link;
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c
> > b/drivers/gpu/drm/i915/i915_gem_context.c
> > index e636d85..3c1b83e 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_context.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> > @@ -298,6 +298,7 @@ __create_hw_context(struct drm_device *dev,
> >  	ctx->ring_size = 4 * PAGE_SIZE;
> >  	ctx->desc_template = GEN8_CTX_ADDRESSING_MODE(dev_priv) <<
> >  		GEN8_CTX_ADDRESSING_MODE_SHIFT;
> > +	ATOMIC_INIT_NOTIFIER_HEAD(&ctx->status_notifier);
> >
> >  	return ctx;
> >
> > diff --git a/drivers/gpu/drm/i915/intel_lrc.c
> > b/drivers/gpu/drm/i915/intel_lrc.c
> > index 2116f86..7f42b15 100644
> > --- a/drivers/gpu/drm/i915/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/intel_lrc.c
> > @@ -404,6 +404,20 @@ static void execlists_submit_requests(struct
> drm_i915_gem_request *rq0,
> >  	spin_unlock_irq(&dev_priv->uncore.lock);
> >  }
> >
> > +static inline void execlists_context_status_change(
> > +		struct drm_i915_gem_request *rq,
> > +		unsigned long status)
> > +{
> > +	/*
> > +	 * Only used when GVT-g is enabled now. When GVT-g is disabled,
> > +	 * The compiler should eliminate this function as dead-code.
> > +	 */
> > +	if (!IS_ENABLED(CONFIG_DRM_I915_GVT))
> > +		return;
> > +
> > +	atomic_notifier_call_chain(&rq->ctx->status_notifier, status, rq); }
> > +
> >  static void execlists_context_unqueue(struct intel_engine_cs *engine)
> >  {
> >  	struct drm_i915_gem_request *req0 = NULL, *req1 = NULL; @@ -439,6
> > +453,12 @@ static void execlists_context_unqueue(struct intel_engine_cs
> *engine)
> >  	if (unlikely(!req0))
> >  		return;
> >
> > +	execlists_context_status_change(req0, INTEL_CONTEXT_SCHEDULE_IN);
> > +
> > +	if (req1)
> > +		execlists_context_status_change(req1,
> > +				INTEL_CONTEXT_SCHEDULE_IN);
> 

No it would exceed 80 characters.

> Indentation is incorrect here. Would it also fit on one line?
> 
> > +
> >  	if (req0->elsp_submitted & engine->idle_lite_restore_wa) {
> >  		/*
> >  		 * WaIdleLiteRestore: make sure we never cause a lite restore @@
> > -477,6 +497,8 @@ execlists_check_remove_request(struct intel_engine_cs
> *engine, u32 ctx_id)
> >  	if (--head_req->elsp_submitted > 0)
> >  		return 0;
> >
> > +	execlists_context_status_change(head_req,
> > +INTEL_CONTEXT_SCHEDULE_OUT);
> > +
> >  	list_del(&head_req->execlist_link);
> >  	i915_gem_request_unreference(head_req);
> >
> > diff --git a/drivers/gpu/drm/i915/intel_lrc.h
> > b/drivers/gpu/drm/i915/intel_lrc.h
> > index a8db42a..2b8255c 100644
> > --- a/drivers/gpu/drm/i915/intel_lrc.h
> > +++ b/drivers/gpu/drm/i915/intel_lrc.h
> > @@ -57,6 +57,11 @@
> >  #define GEN8_CSB_READ_PTR(csb_status) \
> >  	(((csb_status) & GEN8_CSB_READ_PTR_MASK) >> 8)
> >
> > +enum {
> > +	INTEL_CONTEXT_SCHEDULE_IN = 0,
> > +	INTEL_CONTEXT_SCHEDULE_OUT,
> > +};
> > +
> >  /* Logical Rings */
> >  int intel_logical_ring_alloc_request_extras(struct
> > drm_i915_gem_request *request);
> >  int intel_logical_ring_reserve_space(struct drm_i915_gem_request
> > *request);
> --
> Joonas Lahtinen
> Open Source Technology Center
> Intel Corporation