On Fri, 2014-02-21 at 13:06 -0800, Ben Widawsky wrote:
> With the original PPGTT implementation if the number of PDPs was not a
> power of two, the number of pages for the page tables would end up being
> rounded up. The code actually had a bug here afaict, but this is a
> theoretical bug as I don't believe this can actually occur with the
> current code/HW..
>
> With the rework of the page table allocations, there is no longer a
> distinction between number of page table pages, and number of page
> directory entries. To avoid confusion, kill the redundant (and newer)
> struct member.
>
> Cc: Imre Deak <imre.deak@xxxxxxxxx>
> Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx>
Nitpick: keeping num_pt_pages instead would make the code more
understandable to me and symmetric with num_pd_pages, but that would've
been much more churn. In any case nice simplification,
Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 2 +-
> drivers/gpu/drm/i915/i915_drv.h | 3 +--
> drivers/gpu/drm/i915/i915_gem_gtt.c | 14 ++++----------
> 3 files changed, 6 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 509e2e1..e0c42a6 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -1757,7 +1757,7 @@ static void gen8_ppgtt_info(struct seq_file *m, struct drm_device *dev)
> return;
>
> seq_printf(m, "Page directories: %d\n", ppgtt->num_pd_pages);
> - seq_printf(m, "Page tables: %d\n", ppgtt->num_pt_pages);
> + seq_printf(m, "Page tables: %d\n", ppgtt->num_pd_entries);
> for_each_ring(ring, dev_priv, unused) {
> seq_printf(m, "%s\n", ring->name);
> for (i = 0; i < 4; i++) {
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 2f29558..a9f1cae 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -698,13 +698,12 @@ struct i915_hw_ppgtt {
> struct kref ref;
> struct drm_mm_node node;
> unsigned num_pd_entries;
> + unsigned num_pd_pages; /* gen8+ */
> union {
> struct page **pt_pages;
> struct page **gen8_pt_pages[GEN8_LEGACY_PDPS];
> };
> struct page *pd_pages;
> - int num_pd_pages;
> - int num_pt_pages;
> union {
> uint32_t pd_offset;
> dma_addr_t pd_dma_addr[GEN8_LEGACY_PDPS];
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 6c03929..bd815d7 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -433,7 +433,6 @@ static int gen8_ppgtt_allocate_page_tables(struct i915_hw_ppgtt *ppgtt,
> const int max_pdp)
> {
> struct page **pt_pages[GEN8_LEGACY_PDPS];
> - const int num_pt_pages = GEN8_PDES_PER_PAGE * max_pdp;
> int i, ret;
>
> for (i = 0; i < max_pdp; i++) {
> @@ -450,8 +449,6 @@ static int gen8_ppgtt_allocate_page_tables(struct i915_hw_ppgtt *ppgtt,
> for (i = 0; i < max_pdp; i++)
> ppgtt->gen8_pt_pages[i] = pt_pages[i];
>
> - ppgtt->num_pt_pages = 1 << get_order(num_pt_pages << PAGE_SHIFT);
> -
> return 0;
>
> unwind_out:
> @@ -618,18 +615,15 @@ static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt, uint64_t size)
> ppgtt->base.insert_entries = gen8_ppgtt_insert_entries;
> ppgtt->base.cleanup = gen8_ppgtt_cleanup;
> ppgtt->base.start = 0;
> - ppgtt->base.total = ppgtt->num_pt_pages * GEN8_PTES_PER_PAGE * PAGE_SIZE;
> + ppgtt->base.total = ppgtt->num_pd_entries * GEN8_PTES_PER_PAGE * PAGE_SIZE;
>
> - ppgtt->base.clear_range(&ppgtt->base, 0,
> - ppgtt->num_pd_entries * GEN8_PTES_PER_PAGE * PAGE_SIZE,
> - true);
> + ppgtt->base.clear_range(&ppgtt->base, 0, ppgtt->base.total, true);
>
> DRM_DEBUG_DRIVER("Allocated %d pages for page directories (%d wasted)\n",
> ppgtt->num_pd_pages, ppgtt->num_pd_pages - max_pdp);
> DRM_DEBUG_DRIVER("Allocated %d pages for page tables (%lld wasted)\n",
> - ppgtt->num_pt_pages,
> - (ppgtt->num_pt_pages - min_pt_pages) +
> - size % (1<<30));
> + ppgtt->num_pd_entries,
> + (ppgtt->num_pd_entries - min_pt_pages) + size % (1<<30));
> return 0;
>
> bail:
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