[RFC 1/3] HACK: ARM: dma-mapping: Get writeback memory for non-consistent mappings
From: Ezequiel Garcia <hidden>
Date: 2018-08-30 17:21:08
Also in:
linux-media, linux-usb, lkml
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
This is obviously a hack. Signed-off-by: Ezequiel Garcia <redacted> --- arch/arm/include/asm/pgtable.h | 3 +++ arch/arm/mm/dma-mapping.c | 9 ++++++--- 2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index a757401129f9..37ddd0d73434 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h@@ -122,6 +122,9 @@ extern pgprot_t pgprot_s2_device; #define pgprot_writecombine(prot) \ __pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_BUFFERABLE) +#define pgprot_writeback(prot) \ + __pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_WRITEBACK) + #define pgprot_stronglyordered(prot) \ __pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 66566472c153..11cca7bbb0a8 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c@@ -633,9 +633,12 @@ static void __free_from_contiguous(struct device *dev, struct page *page, static inline pgprot_t __get_dma_pgprot(unsigned long attrs, pgprot_t prot) { - prot = (attrs & DMA_ATTR_WRITE_COMBINE) ? - pgprot_writecombine(prot) : - pgprot_dmacoherent(prot); + if (attrs & DMA_ATTR_WRITE_COMBINE) + prot = pgprot_writecombine(prot); + else if (attrs & DMA_ATTR_NON_CONSISTENT) + prot = pgprot_writeback(prot); + else + prot = pgprot_dmacoherent(prot); return prot; }
--
2.18.0