Re: [PATCH 09/21] riscv: dma-mapping: skip invalidation before bidirectional DMA
From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date: 2023-03-30 13:27:15
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linux-arm-kernel, linux-m68k, linux-mips, linux-riscv, linux-sh, lkml, sparclinux
On Mon, Mar 27, 2023 at 1:16 PM Arnd Bergmann [off-list ref] wrote:
From: Arnd Bergmann <arnd@arndb.de> 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 <arnd@arndb.de> --- arch/riscv/mm/dma-noncoherent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Cheers, Prabhakar
quoted hunk ↗ jump to hunk
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c index 640f4c496d26..69c80b2155a1 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; --2.39.2 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv