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[10/21] csky: dma-mapping: skip invalidating before DMA from device

Message ID 20230327121317.4081816-11-arnd@kernel.org (mailing list archive)
State New, archived
Headers show
Series dma-mapping: unify support for cache flushes | expand

Commit Message

Arnd Bergmann March 27, 2023, 12:13 p.m. UTC 
From: Arnd Bergmann <arnd@arndb.de>

csky is the only architecture that does a full flush for the
dma_sync_*_for_device(..., DMA_FROM_DEVICE) operation. The requirement
is only make sure there are no dirty cache lines for the buffer,
which can be either done through an invalidate operation (as on most
architectures including arm32, mips and arc), or a writeback (as on
arm64 and riscv). The cache also has to be invalidated eventually but
csky already does that after the transfer.

Use a 'clean' operation here for consistency with arm64 and riscv.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/csky/mm/dma-mapping.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Comments

Guo Ren March 27, 2023, 1:37 p.m. UTC | #1 
On Mon, Mar 27, 2023 at 8:15 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> csky is the only architecture that does a full flush for the
> dma_sync_*_for_device(..., DMA_FROM_DEVICE) operation. The requirement
> is only make sure there are no dirty cache lines for the buffer,
> which can be either done through an invalidate operation (as on most
> architectures including arm32, mips and arc), or a writeback (as on
> arm64 and riscv). The cache also has to be invalidated eventually but
> csky already does that after the transfer.
>
> Use a 'clean' operation here for consistency with arm64 and riscv.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/csky/mm/dma-mapping.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/csky/mm/dma-mapping.c b/arch/csky/mm/dma-mapping.c
> index 82447029feb4..c90f912e2822 100644
> --- a/arch/csky/mm/dma-mapping.c
> +++ b/arch/csky/mm/dma-mapping.c
> @@ -60,11 +60,9 @@ void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>  {
>         switch (dir) {
>         case DMA_TO_DEVICE:
> -               cache_op(paddr, size, dma_wb_range);
> -               break;
>         case DMA_FROM_DEVICE:
>         case DMA_BIDIRECTIONAL:
> -               cache_op(paddr, size, dma_wbinv_range);
> +               cache_op(paddr, size, dma_wb_range);
Reviewed-by: Guo Ren <guoren@kernel.org>


>                 break;
>         default:
>                 BUG();
> --
> 2.39.2
>
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Patch

diff --git a/arch/csky/mm/dma-mapping.c b/arch/csky/mm/dma-mapping.c
index 82447029feb4..c90f912e2822 100644
--- a/arch/csky/mm/dma-mapping.c
+++ b/arch/csky/mm/dma-mapping.c
@@ -60,11 +60,9 @@  void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
 {
 	switch (dir) {
 	case DMA_TO_DEVICE:
-		cache_op(paddr, size, dma_wb_range);
-		break;
 	case DMA_FROM_DEVICE:
 	case DMA_BIDIRECTIONAL:
-		cache_op(paddr, size, dma_wbinv_range);
+		cache_op(paddr, size, dma_wb_range);
 		break;
 	default:
 		BUG();