[PATCH v2] drm/ttm: expose CPU address of DMA-allocated pages

From: Alexandre Courbot
Date: Mon Aug 04 2014 - 05:29:18 EST


Pages allocated using the DMA API have a coherent memory mapping. Make
this mapping visible to drivers so they can decide to use it instead of
creating their own redundant one.

Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
Acked-by: David Airlie <airlied@xxxxxxxx>
---
Changes since v1:
- Perform only one allocation for pages, CPU and DMA addresses
- Added David's ack

drivers/gpu/drm/ttm/ttm_page_alloc_dma.c | 2 ++
drivers/gpu/drm/ttm/ttm_tt.c | 13 ++++++++-----
include/drm/ttm/ttm_bo_driver.h | 2 ++
3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index fb8259f69839..0301fac5badd 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -847,6 +847,7 @@ static int ttm_dma_pool_get_pages(struct dma_pool *pool,
if (count) {
d_page = list_first_entry(&pool->free_list, struct dma_page, page_list);
ttm->pages[index] = d_page->p;
+ ttm_dma->cpu_address[index] = d_page->vaddr;
ttm_dma->dma_address[index] = d_page->dma;
list_move_tail(&d_page->page_list, &ttm_dma->pages_list);
r = 0;
@@ -978,6 +979,7 @@ void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
INIT_LIST_HEAD(&ttm_dma->pages_list);
for (i = 0; i < ttm->num_pages; i++) {
ttm->pages[i] = NULL;
+ ttm_dma->cpu_address[i] = 0;
ttm_dma->dma_address[i] = 0;
}

diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 75f319090043..bf080abc86d1 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -55,9 +55,12 @@ static void ttm_tt_alloc_page_directory(struct ttm_tt *ttm)

static void ttm_dma_tt_alloc_page_directory(struct ttm_dma_tt *ttm)
{
- ttm->ttm.pages = drm_calloc_large(ttm->ttm.num_pages, sizeof(void*));
- ttm->dma_address = drm_calloc_large(ttm->ttm.num_pages,
- sizeof(*ttm->dma_address));
+ ttm->ttm.pages = drm_calloc_large(ttm->ttm.num_pages,
+ sizeof(*ttm->ttm.pages) +
+ sizeof(*ttm->dma_address) +
+ sizeof(*ttm->cpu_address));
+ ttm->cpu_address = (void *) (ttm->ttm.pages + ttm->ttm.num_pages);
+ ttm->dma_address = (void *) (ttm->cpu_address + ttm->ttm.num_pages);
}

#ifdef CONFIG_X86
@@ -228,7 +231,7 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,

INIT_LIST_HEAD(&ttm_dma->pages_list);
ttm_dma_tt_alloc_page_directory(ttm_dma);
- if (!ttm->pages || !ttm_dma->dma_address) {
+ if (!ttm->pages) {
ttm_tt_destroy(ttm);
pr_err("Failed allocating page table\n");
return -ENOMEM;
@@ -243,7 +246,7 @@ void ttm_dma_tt_fini(struct ttm_dma_tt *ttm_dma)

drm_free_large(ttm->pages);
ttm->pages = NULL;
- drm_free_large(ttm_dma->dma_address);
+ ttm_dma->cpu_address = NULL;
ttm_dma->dma_address = NULL;
}
EXPORT_SYMBOL(ttm_dma_tt_fini);
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 202f0a7171e8..1d9f0f1ff52d 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -133,6 +133,7 @@ struct ttm_tt {
* struct ttm_dma_tt
*
* @ttm: Base ttm_tt struct.
+ * @cpu_address: The CPU address of the pages
* @dma_address: The DMA (bus) addresses of the pages
* @pages_list: used by some page allocation backend
*
@@ -142,6 +143,7 @@ struct ttm_tt {
*/
struct ttm_dma_tt {
struct ttm_tt ttm;
+ void **cpu_address;
dma_addr_t *dma_address;
struct list_head pages_list;
};
--
2.0.3

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