drm/i915: Remove unnecessary gen8_clamp_pd

gen8_clamp_pd clamps to the next page directory boundary, but the macro
gen8_for_each_pde already has a check to stop at the page directory
boundary.

Furthermore, i915_pte_count also restricts to the next page table
boundary.

v2: Rebase after Mika's ppgtt cleanup / scratch merge patch series.
Suggested-by: NAkash Goel <akash.goel@intel.com>
Signed-off-by: NMichel Thierry <michel.thierry@intel.com>
Reviewed-by: N"Akash Goel" <akash.goel@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -955,7 +955,7 @@ static int gen8_alloc_va_range(struct i915_address_space *vm,
 	gen8_for_each_pdpe(pd, &ppgtt->pdp, start, length, temp, pdpe) {
 		gen8_pde_t *const page_directory = kmap_px(pd);
 		struct i915_page_table *pt;
-		uint64_t pd_len = gen8_clamp_pd(start, length);
+		uint64_t pd_len = length;
 		uint64_t pd_start = start;
 		uint32_t pde;
 

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -444,17 +444,6 @@ static inline uint32_t gen6_pde_index(uint32_t addr)
 	     temp = min(temp, length),					\
 	     start += temp, length -= temp)
 
-/* Clamp length to the next page_directory boundary */
-static inline uint64_t gen8_clamp_pd(uint64_t start, uint64_t length)
-{
-	uint64_t next_pd = ALIGN(start + 1, 1 << GEN8_PDPE_SHIFT);
-
-	if (next_pd > (start + length))
-		return length;
-
-	return next_pd - start;
-}
-
 static inline uint32_t gen8_pte_index(uint64_t address)
 {
 	return i915_pte_index(address, GEN8_PDE_SHIFT);