Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 29 Mar 2023 21:16:10 +0100
From:   Conor Dooley <conor@kernel.org>
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
        Vineet Gupta <vgupta@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
        Brian Cain <bcain@quicinc.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Michal Simek <monstr@monstr.eu>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Dinh Nguyen <dinguyen@kernel.org>,
        Stafford Horne <shorne@gmail.com>,
        Helge Deller <deller@gmx.de>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Rich Felker <dalias@libc.org>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        "David S. Miller" <davem@davemloft.net>,
        Max Filippov <jcmvbkbc@gmail.com>,
        Christoph Hellwig <hch@lst.de>,
        Robin Murphy <robin.murphy@arm.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        Conor Dooley <conor.dooley@microchip.com>,
        linux-snps-arc@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-oxnas@groups.io,
        linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org,
        linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
        linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
        linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
        linux-xtensa@linux-xtensa.org
Subject: Re: [PATCH 09/21] riscv: dma-mapping: skip invalidation before
 bidirectional DMA
Message-ID: <764e8d2f-ed98-49dc-8fdb-112d59359148@spud>
References: <20230327121317.4081816-1-arnd@kernel.org>
 <20230327121317.4081816-10-arnd@kernel.org>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256;
        protocol="application/pgp-signature"; boundary="2LJh6dsRB07q9YeN"
Content-Disposition: inline
In-Reply-To: <20230327121317.4081816-10-arnd@kernel.org>
Precedence: bulk


--2LJh6dsRB07q9YeN
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Mon, Mar 27, 2023 at 02:13:05PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>=20
> 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.
>=20
> riscv also invalidates the caches before the transfer, which does
> not appear to serve any purpose.

Rationale makes sense to me..
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Thanks for working on all of this Arnd!

--2LJh6dsRB07q9YeN
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZCScigAKCRB4tDGHoIJi
0jHpAP47kMhf2uxHoGKhD+jHsEYnFgTHptLnAfIJV6N+QeFoOAD/YxG6hd8qhesW
6Tw9EqBEW/4auX2CLsbK7xE8fP5A9wg=
=os1C
-----END PGP SIGNATURE-----

--2LJh6dsRB07q9YeN--