Quoting Tvrtko Ursulin (2018-09-14 11:03:03) > > On 14/09/2018 10:47, Chris Wilson wrote: > > Quoting Tvrtko Ursulin (2018-09-14 10:40:43) > >> > >> On 14/09/2018 09:34, Chris Wilson wrote: > >>> Once we have flushed the first request through the system to both load a > >>> context and record the default state; tell the GPU to park and idle > >>> itself, putting itself immediately (hopefully at least) into a > >>> powersaving state, and allowing ourselves to start from known state > >>> after setting up all our bookkeeping. > >> > >> Otherwise this would happen after a second or so, when the idle work > >> handler does it. Crucial thing to mention is I think the park/unpark > >> cycle which sets up the pinned default state. > > > > Hmm, I didn't think it was worth highlight it here as one assumes that > > all the bookkeeping is equally required :) I pulled out for special > > mention in the comment, because I thought that was relevant to the > > function where we are acquiring the default_state. > > > >> Alternative to patch could be to extract > >> __intel_engine_pin_default_state to be called from here and from > >> intel_engines_unpark. > >> > >> But I guess there is some value in going powersave as soon as possible > >> so okay. > > > > Yeah. Later on (as in patches that have been on the ml for several > > months with feature requests depending on them...) we acquire a > > load_powersaving_context() function, which should make this a little more > > interesting. > > > >>> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >>> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > >>> --- > >>> drivers/gpu/drm/i915/i915_gem.c | 8 ++++++++ > >>> 1 file changed, 8 insertions(+) > >>> > >>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > >>> index 89834ce19acd..be9d012d851b 100644 > >>> --- a/drivers/gpu/drm/i915/i915_gem.c > >>> +++ b/drivers/gpu/drm/i915/i915_gem.c > >>> @@ -5414,6 +5414,14 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915) > >>> > >>> assert_kernel_context_is_current(i915); > >>> > >>> + /* > >>> + * Immediately park the GPU so that we enable powersaving and > >>> + * treat it as idle. The next time we issue a request, we will > >>> + * unpark and start using the engine->pinned_default_state, otherwise > >>> + * it is in limbo and an early reset may fail. > >>> + */ > >>> + __i915_gem_park(i915); > >> > >> Why not after we have grabbed the default state? > > > > I was just wanting to tie it to the switch to kernel-context + idle. > > I was thinking this was the closed point to the normal park sequence. > > > >> I was worried this might access a sleeping device but apparently at > >> least vma unbind takes the rpm ref. Still, just this I think makes it > >> more logical to park after we have grabbed the default state, instead o > >> putting the device to sleep and then immediately waking up below. > > > > Oh, we have wakerefs aplenty on module load, we are not assuming gt.awake > > here. > > Now I am having doubts if it is a business of > __intel_engines_record_defaults to park the engines, or the caller > (i915_gem_init) would be a better design.. Hmm, nah, you're just reading too much specificity into record_defaults :-p -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
