drm/i915/gt: Optimise aliasing-ppgtt allocations

Since the aliasing-ppgtt remains the default for gen6/gen7, it is worth
optimising the ppgtt allocation for it. In this case, we do not need to
flush the GGTT page directories entries as they are fixed during setup.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200709190111.5492-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
index 05497b50103f283395f3b44d82dfe2db9149f6be..cdc0b9c54305b79eb6f161cc2fee30d1ee9991f6 100644 (file)
--- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
@@ -183,13 +183,11 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
        struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));
        struct i915_page_directory * const pd = ppgtt->base.pd;
        struct i915_page_table *pt, *alloc = NULL;
-       intel_wakeref_t wakeref;
+       bool flush = false;
        u64 from = start;
        unsigned int pde;
        int ret = 0;
 
-       wakeref = intel_runtime_pm_get(&vm->i915->runtime_pm);
-
        spin_lock(&pd->lock);
        gen6_for_each_pde(pt, pd, start, length, pde) {
                const unsigned int count = gen6_pte_count(start, length);
@@ -214,14 +212,20 @@ static int gen6_alloc_va_range(struct i915_address_space *vm,
                                alloc = pt;
                                pt = pd->entry[pde];
                        }
+
+                       flush = true;
                }
 
                atomic_add(count, &pt->used);
        }
        spin_unlock(&pd->lock);
 
-       if (i915_vma_is_bound(ppgtt->vma, I915_VMA_GLOBAL_BIND))
-               gen6_flush_pd(ppgtt, from, start);
+       if (flush && i915_vma_is_bound(ppgtt->vma, I915_VMA_GLOBAL_BIND)) {
+               intel_wakeref_t wakeref;
+
+               with_intel_runtime_pm(&vm->i915->runtime_pm, wakeref)
+                       gen6_flush_pd(ppgtt, from, start);
+       }
 
        goto out;
 
@@ -230,7 +234,6 @@ unwind_out:
 out:
        if (alloc)
                free_px(vm, alloc);
-       intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);
        return ret;
 }