From 482069ebdc1d61fba14527055894b9f4f0ced08c Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 17 Aug 2023 00:23:35 +0100 Subject: [PATCH] riscv: dma-mapping: skip invalidation before bidirectional DMA For a DMA_BIDIRECTIONAL transfer, the caches have to be cleaned first to let the device see data written by the CPU, and invalidated after the transfer to let the CPU see data written by the device. riscv also invalidates the caches before the transfer, which does not appear to serve any purpose. Signed-off-by: Arnd Bergmann Reviewed-by: Conor Dooley Reviewed-by: Lad Prabhakar Acked-by: Palmer Dabbelt Acked-by: Guo Ren Signed-off-by: Lad Prabhakar Link: https://lore.kernel.org/r/20230816232336.164413-3-prabhakar.mahadev-lad.rj@bp.renesas.com Signed-off-by: Palmer Dabbelt --- arch/riscv/mm/dma-noncoherent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c index 94614cf..fc6377a 100644 --- a/arch/riscv/mm/dma-noncoherent.c +++ b/arch/riscv/mm/dma-noncoherent.c @@ -25,7 +25,7 @@ void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size); break; case DMA_BIDIRECTIONAL: - ALT_CMO_OP(flush, vaddr, size, riscv_cbom_block_size); + ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size); break; default: break; -- 2.7.4