On Thu, 2017-11-02 at 12:42 +0000, Chris Wilson wrote:
> Take a copy of the HW state after a reset upon module loading by
> executing a context switch from a blank context to the kernel context,
> thus saving the default hw state over the blank context image.
> We can then use the default hw state to initialise any future context,
> ensuring that each starts with the default view of hw state.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
<SNIP>
> @@ -795,11 +770,7 @@ static int do_rcs_switch(struct drm_i915_gem_request *req)
> return ret;
> }
>
> - if (!to->engine[RCS].initialised || i915_gem_context_is_default(to))
> - /* NB: If we inhibit the restore, the context is not allowed to
> - * die because future work may end up depending on valid address
> - * space. This means we must enforce that a page table load
> - * occur when this occurs. */
Maybe add a comment explaining that we never ever assume execution on
the kernel context, so we don't care about the register state.
> + if (i915_gem_context_is_kernel(to))
> hw_flags = MI_RESTORE_INHIBIT;
> else if (ppgtt && intel_engine_flag(engine) & ppgtt->pd_dirty_rings)
> hw_flags = MI_FORCE_RESTORE;
<SNIP>
> @@ -2193,11 +2184,28 @@ populate_lr_context(struct i915_gem_context *ctx,
> }
> ctx_obj->mm.dirty = true;
>
> + if (engine->default_state) {
> + void *defaults;
> +
> + defaults = i915_gem_object_pin_map(engine->default_state,
> + I915_MAP_WB);
> + if (IS_ERR(defaults))
> + return PTR_ERR(defaults);
> +
> + memcpy(vaddr + LRC_HEADER_PAGES * PAGE_SIZE,
> + defaults + LRC_HEADER_PAGES * PAGE_SIZE,
Could use somethingsomething_offset variable.
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Regards, Joonas
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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