On Tue, Dec 23, 2014 at 05:16:14PM +0000, Michel Thierry wrote:
> From: Ben Widawsky <benjamin.widawsky@xxxxxxxxx>
>
> We have some fanciness coming up. This patch just breaks out the logic
> of context switch skip, pd load pre, and pd load post.
>
> v2: Use new functions to replace the logic right away (Daniel)
>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx>
> Signed-off-by: Michel Thierry <michel.thierry@xxxxxxxxx> (v2)
Since we won't ever ship gen8+ without execlist and full ppgtt legacy
context switching special-cases for that are kinda moot. But something we
could simplify with a follow-up patch once the series has landed, together
with some checks to make sure we don't try to reload the ppgtt on gen8+
ever.
-Daniel
> ---
> drivers/gpu/drm/i915/i915_gem_context.c | 40 +++++++++++++++++++++++++--------
> 1 file changed, 31 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index b67d269..7b20bd4 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -563,6 +563,33 @@ mi_set_context(struct intel_engine_cs *ring,
> return ret;
> }
>
> +static inline bool should_skip_switch(struct intel_engine_cs *ring,
> + struct intel_context *from,
> + struct intel_context *to)
> +{
> + if (from == to && !to->remap_slice)
> + return true;
> +
> + return false;
> +}
> +
> +static bool
> +needs_pd_load_pre(struct intel_engine_cs *ring, struct intel_context *to)
> +{
> + struct drm_i915_private *dev_priv = ring->dev->dev_private;
> +
> + return ((INTEL_INFO(ring->dev)->gen < 8) ||
> + (ring != &dev_priv->ring[RCS])) && to->ppgtt;
> +}
> +
> +static bool
> +needs_pd_load_post(struct intel_engine_cs *ring, struct intel_context *to)
> +{
> + return (!to->legacy_hw_ctx.initialized ||
> + i915_gem_context_is_default(to)) &&
> + to->ppgtt && IS_GEN8(ring->dev);
> +}
> +
> static int do_switch(struct intel_engine_cs *ring,
> struct intel_context *to)
> {
> @@ -571,9 +598,6 @@ static int do_switch(struct intel_engine_cs *ring,
> u32 hw_flags = 0;
> bool uninitialized = false;
> struct i915_vma *vma;
> - bool needs_pd_load_pre = ((INTEL_INFO(ring->dev)->gen < 8) ||
> - (ring != &dev_priv->ring[RCS])) && to->ppgtt;
> - bool needs_pd_load_post = false;
> int ret, i;
>
> if (from != NULL && ring == &dev_priv->ring[RCS]) {
> @@ -581,7 +605,7 @@ static int do_switch(struct intel_engine_cs *ring,
> BUG_ON(!i915_gem_obj_is_pinned(from->legacy_hw_ctx.rcs_state));
> }
>
> - if (from == to && !to->remap_slice)
> + if (should_skip_switch(ring, from, to))
> return 0;
>
> /* Trying to pin first makes error handling easier. */
> @@ -599,7 +623,7 @@ static int do_switch(struct intel_engine_cs *ring,
> */
> from = ring->last_context;
>
> - if (needs_pd_load_pre) {
> + if (needs_pd_load_pre(ring, to)) {
> /* Older GENs and non render rings still want the load first,
> * "PP_DCLV followed by PP_DIR_BASE register through Load
> * Register Immediate commands in Ring Buffer before submitting
> @@ -644,16 +668,14 @@ static int do_switch(struct intel_engine_cs *ring,
> * XXX: If we implemented page directory eviction code, this
> * optimization needs to be removed.
> */
> - if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to)) {
> + if (!to->legacy_hw_ctx.initialized || i915_gem_context_is_default(to))
> hw_flags |= MI_RESTORE_INHIBIT;
> - needs_pd_load_post = to->ppgtt && IS_GEN8(ring->dev);
> - }
>
> ret = mi_set_context(ring, to, hw_flags);
> if (ret)
> goto unpin_out;
>
> - if (needs_pd_load_post) {
> + if (needs_pd_load_post(ring, to)) {
> ret = to->ppgtt->switch_mm(to->ppgtt, ring);
> /* The hardware context switch is emitted, but we haven't
> * actually changed the state - so it's probably safe to bail
> --
> 2.1.1
>
> _______________________________________________
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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