Re: [PATCH 1/2] rendercopy/bdw: Enable hw-generated binding tables

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

On Thu, May 08, 2014 at 12:54:47PM +0300, Ville Syrjälä wrote:
> On Wed, May 07, 2014 at 11:59:23PM +0300, Abdiel Janulgue wrote:
> > On Wednesday, May 07, 2014 02:49:31 PM Ville Syrjälä wrote:
> > > I quickly cobbled together a hsw version of this and gave it a whirl on
> > > one machine. Seems to work just fine here, and no lockups when switching
> > > between hw and sw binding tables. Did you get the lockups on hsw even
> > > with rendercopy?
> > > 
> > > Here's my hsw version:
> > > 
> > > 
> > > +static void
> > > +gen7_hw_binding_table(struct intel_batchbuffer *batch, bool enable)
> > > +{
> > > +	if (!enable) {
> > > +		OUT_BATCH(MI_RS_CONTROL | 0x0);
> > > +
> > > +		OUT_BATCH(HSW_3DSTATE_BINDING_TABLE_POOL_ALLOC | (3 - 2));
> > > +		/* binding table pool base address */
> > 
> > This bit I missed and the source of my troubles for the past few months.
> > 
> > > +		OUT_BATCH(3 << 5);
> > 
> > Yep, I confirm toggling on HSW does work quite well now. I'll now update the 
> > patches to include HSW path on the kernel. I also take back my previous 
> > statement that RS is broken on HSW! :)
> 
> Excellent.
> 
> I was wondering a bit if we need to make the kernel turn off the hw
> binding tables between batches, but since we now have per fd default
> contexts and 3DSTATE_BINDING_TABLE_POOL_ALLOC should be saved in the
> context, maybe we don't actually need to do that. Although it seems
> like that would cause problems when we switch to the global default
> context since we use the restore_inhibit flag there. So maybe we need
> to special case the default context here and force the hw binding
> tables off when switching to it.

Ah actually we still inhibit restore even with the per-file default
contexts. So I guess it's going to be a problemn whenever we switch
to any default context and the hw binding tables were left enabled.

So I guess there are two options: either drop the restore_inhibit flag
for default contexts (I kind of like this idea but maybe other people
hate it), or have the kernel turn off the hw binding tables when
switching to any default context. The latter would also imply that if
user space wants to use the resource streamer with the default context,
it has to turn the binding tables on at the start of every batch since
it can't know whether the kernel turned them off.

-- 
Ville Syrjälä
Intel OTC