On 24/01/18 02:56, Gurchetan Singh wrote:
This patch uses the __dma_map_area function to flush the cache
on ARM64.
v2: Don't use DMA API, call functions directly (Daniel)
Signed-off-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
---
drivers/gpu/drm/drm_cache.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
index 5124582451c6..250cdfbb711f 100644
--- a/drivers/gpu/drm/drm_cache.c
+++ b/drivers/gpu/drm/drm_cache.c
@@ -159,6 +159,12 @@ drm_flush_pages(struct page *pages[], unsigned long num_pages)
for (i = 0; i < num_pages; i++)
drm_cache_maint_page(pages[i], 0, PAGE_SIZE, DMA_TO_DEVICE,
dmac_map_area);
+#elif defined(CONFIG_ARM64)
+ unsigned long i;
+
+ for (i = 0; i < num_pages; i++)
+ __dma_map_area(phys_to_virt(page_to_phys(pages[i])), PAGE_SIZE,
+ DMA_TO_DEVICE);
Note that this is not exactly equivalent to clflush - if it's at all
possible for a non-coherent GPU to write back to these pages and someone
somewhere expects to be able to read the updated data from a CPU, that's
going to be subtly broken.
This also breaks building DRM as a module. And I doubt that either of
the two easy solutions to that are going to fly with the respective
maintainers...
Given all the bodging around which seems to happen in DRM/ION/etc., it
would be really nice to pin down what exactly the shortcomings of the
DMA API are for these use-cases, and extend it to address them properly.
Robin.
#else
pr_err("Architecture has no drm_cache.c support\n");
WARN_ON_ONCE(1);
@@ -196,6 +202,13 @@ drm_flush_sg(struct sg_table *st)
for_each_sg_page(st->sgl, &sg_iter, st->nents, 0)
drm_cache_maint_page(sg_page_iter_page(&sg_iter), 0, PAGE_SIZE,
DMA_TO_DEVICE, dmac_map_area);
+#elif defined(CONFIG_ARM64)
+ int i;
+ struct scatterlist *sg;
+
+ for_each_sg(st->sgl, sg, st->nents, i)
+ __dma_map_area(phys_to_virt(sg_phys(sg)), sg->length,
+ DMA_TO_DEVICE);
#else
pr_err("Architecture has no drm_cache.c support\n");
WARN_ON_ONCE(1);
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel
