This way allocations like the NVMe HMB don't consume iomap space
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
Note: compile tested only, I stumbled over this when researching dma api
quirks for HMB support.
arch/arc/mm/dma.c | 42 +++++++++++++++++++++++++++++-------------
1 file changed, 29 insertions(+), 13 deletions(-)
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 2a07e6ecafbd..d8999ac88879 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -28,13 +28,22 @@ static void *arc_dma_alloc(struct device *dev, size_t size,
struct page *page;
phys_addr_t paddr;
void *kvaddr;
- int need_coh = 1, need_kvaddr = 0;
+ bool need_cache_sync = true, need_kvaddr = false;
page = alloc_pages(gfp, order);
if (!page)
return NULL;
/*
+ * No-kernel mapping memoery doesn't need a kernel virtual address.
+ * But we do the initial cache flush to make sure we don't write back
+ * to from a previous mapping into the now device owned memory.
+ */
+ if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
+ need_cache_sync = true;
+ need_kvaddr = false;
+
+ /*
* IOC relies on all data (even coherent DMA data) being in cache
* Thus allocate normal cached memory
*
@@ -45,17 +54,19 @@ static void *arc_dma_alloc(struct device *dev, size_t size,
* -For coherent data, Read/Write to buffers terminate early in cache
* (vs. always going to memory - thus are faster)
*/
- if ((is_isa_arcv2() && ioc_enable) ||
- (attrs & DMA_ATTR_NON_CONSISTENT))
- need_coh = 0;
+ } else if ((is_isa_arcv2() && ioc_enable) ||
+ (attrs & DMA_ATTR_NON_CONSISTENT)) {
+ need_cache_sync = false;
+ need_kvaddr = true;
/*
* - A coherent buffer needs MMU mapping to enforce non-cachability
* - A highmem page needs a virtual handle (hence MMU mapping)
* independent of cachability
*/
- if (PageHighMem(page) || need_coh)
- need_kvaddr = 1;
+ } else if (PageHighMem(page)) {
+ need_kvaddr = true;
+ }
/* This is linear addr (0x8000_0000 based) */
paddr = page_to_phys(page);
@@ -83,7 +94,7 @@ static void *arc_dma_alloc(struct device *dev, size_t size,
* Currently flush_cache_vmap nukes the L1 cache completely which
* will be optimized as a separate commit
*/
- if (need_coh)
+ if (need_cache_sync)
dma_cache_wback_inv(paddr, size);
return kvaddr;
@@ -93,14 +104,19 @@ static void arc_dma_free(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle, unsigned long attrs)
{
phys_addr_t paddr = plat_dma_to_phys(dev, dma_handle);
- struct page *page = virt_to_page(paddr);
- int is_non_coh = 1;
- is_non_coh = (attrs & DMA_ATTR_NON_CONSISTENT) ||
- (is_isa_arcv2() && ioc_enable);
+ if (!(attrs & DMA_ATTR_NO_KERNEL_MAPPING)) {
+ struct page *page = virt_to_page(paddr);
+ bool need_iounmap = true;
+
+ if (!PageHighMem(page) &&
+ ((is_isa_arcv2() && ioc_enable) ||
+ (attrs & DMA_ATTR_NON_CONSISTENT)))
+ need_iounmap = false;
- if (PageHighMem(page) || !is_non_coh)
- iounmap((void __force __iomem *)vaddr);
+ if (need_iounmap)
+ iounmap((void __force __iomem *)vaddr);
+ }
__free_pages(page, get_order(size));
}
--
2.11.0
