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

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Message-Id: <20230327121317.4081816-11-arnd@kernel.org>
Date:   Mon, 27 Mar 2023 14:13:06 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>, Vineet Gupta <vgupta@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        Brian Cain <bcain@...cinc.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Michal Simek <monstr@...str.eu>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Stafford Horne <shorne@...il.com>,
        Helge Deller <deller@....de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Rich Felker <dalias@...c.org>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        "David S. Miller" <davem@...emloft.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        Christoph Hellwig <hch@....de>,
        Robin Murphy <robin.murphy@....com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-oxnas@...ups.io,
        linux-csky@...r.kernel.org, linux-hexagon@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
        linux-openrisc@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org
Subject: [PATCH 10/21] csky: dma-mapping: skip invalidating before DMA from device

From: Arnd Bergmann <arnd@...db.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@...db.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);
 		break;
 	default:
 		BUG();
-- 
2.39.2