On Fri, Aug 22, 2014 at 01:10:26PM +0100, Siluvery, Arun wrote: > On 22/08/2014 12:06, Mika Kuoppala wrote: > >Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> writes: > > > >>On Wed, Aug 20, 2014 at 03:19:17PM +0100, Arun Siluvery wrote: > >>>Workarounds for bdw are currently applied in init_clock_gating() but they > >>>are lost following a gpu reset. Some of the WA registers are part of register > >>>state context and they are restored with every context switch so initializing > >>>them in golden render state ensures that they are applied even when we start > >>>with an uninitialized context or during hw initlialization followed by a reset. > >>> > >>>v2: Add comments corresponding to WAs in golden render state (Chris). > >>> > >>>The generation of render state is not a straighforward process, it would > >>>be ideal to augment WA values from during the setup state as opposed to > >>>using a tool but that would be a follow up patch. > >> > >>I'd still prefer just emitting the LRIs from code rather tha mucking > >>about with null batch. Less hoops to jump through when adding a new w/a. > > > >I agree with this. We should aim to keep null state as per > >gen. Workaround set is different for gtX inside particular > >gen so we would need then multiple null states per gen. > > > >After brief chat with Ville, I think that the correct > >spot to init the context specific workarounds is after MI_SET_CONTEXT > >to default and right before null batch is run. If we do these > >with emitting LRIs to ring, we should be safe as they are then saved > >with default ctx. > > > >The default ctx is then used as a 'parent' for newly created > >contexts. Ofcource if registers get globbered, then we inherit > >crap. > > > >If we have the per gen null state and the ring is initializing > >workarounds for the default context, then in future we can > >save this state as 'read only golden context'. And use it as the > >initial state for all newly created contexts. > > > >Then the full plan how to init would look like this: > > > >#1 reset the gpu (on driver load, on resume or on hang recovery) > >#2 if we have 'read only golden context', copy it to default ctx > >#3 switch to default context > >#4 if we had 'read only golden context' we are done with the init. > > > >--- > > > >#5 if this is driver load thus there is no 'read only golden context' yet. > >#6 init workarounds through ring LRIs > >#7 run null/golden state batch > >#8 save this state as a 'read only golden context' > > > >--- > > > >#9 for each new context, initialize ctx obj with 'read only golden > > context' (either by memcpy or restoring from it when switching to new) > > > I understand applying WAs using null batch has its issues but as I mentioned > in the commit msg I will fix this as a follow up patch. > It is going to take some time though to change the patch as per the new > sequence. > The patch in its current state helps fix WA issues after reset; so it can > only be accepted if it is updated as per the new sequence? We already have a lot of "let's fix it later" experiments running, so I don't want to overload the ship. So I highly prefer to merge the revised version directly. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
