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From: Christoph Hellwig <hch@lst.de>
To: "Heiko Stübner" <heiko@sntech.de>
Cc: Christoph Hellwig <hch@lst.de>,
	palmer@dabbelt.com, paul.walmsley@sifive.com,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	wefu@redhat.com, guoren@kernel.org, cmuellner@linux.com,
	philipp.tomsich@vrull.eu, samuel@sholland.org,
	atishp@atishpatra.org, anup@brainfault.org, mick@ics.forth.gr,
	robh+dt@kernel.org, krzk+dt@kernel.org,
	devicetree@vger.kernel.org, drew@beagleboard.org,
	Atish Patra <atish.patra@wdc.com>
Subject: Re: [PATCH 2/3] riscv: Implement Zicbom-based cache management operations
Date: Thu, 16 Jun 2022 14:11:57 +0200	[thread overview]
Message-ID: <20220616121157.GA11657@lst.de> (raw)
In-Reply-To: <2041345.KlZ2vcFHjT@diego>

On Thu, Jun 16, 2022 at 02:09:47PM +0200, Heiko Stübner wrote:
> My guess was that new platforms implementing cache-management will want
> to be non-coherent by default?

No.  Cache incoherent DMA is absolutely horrible and almost impossible
to get right for the corner cases.  It is a cost cutting measure seen on
cheap SOCs and mostly avoided for more enterprise grade products.

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linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: "Heiko Stübner" <heiko@sntech.de>
Cc: Christoph Hellwig <hch@lst.de>,
	palmer@dabbelt.com, paul.walmsley@sifive.com,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	wefu@redhat.com, guoren@kernel.org, cmuellner@linux.com,
	philipp.tomsich@vrull.eu, samuel@sholland.org,
	atishp@atishpatra.org, anup@brainfault.org, mick@ics.forth.gr,
	robh+dt@kernel.org, krzk+dt@kernel.org,
	devicetree@vger.kernel.org, drew@beagleboard.org,
	Atish Patra <atish.patra@wdc.com>
Subject: Re: [PATCH 2/3] riscv: Implement Zicbom-based cache management operations
Date: Thu, 16 Jun 2022 14:11:57 +0200	[thread overview]
Message-ID: <20220616121157.GA11657@lst.de> (raw)
In-Reply-To: <2041345.KlZ2vcFHjT@diego>

On Thu, Jun 16, 2022 at 02:09:47PM +0200, Heiko Stübner wrote:
> My guess was that new platforms implementing cache-management will want
> to be non-coherent by default?

No.  Cache incoherent DMA is absolutely horrible and almost impossible
to get right for the corner cases.  It is a cost cutting measure seen on
cheap SOCs and mostly avoided for more enterprise grade products.

  reply	other threads:[~2022-06-16 12:12 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-10  0:43 [PATCH v3 0/3] riscv: implement Zicbom-based CMO instructions + the t-head variant Heiko Stuebner
2022-06-10  0:43 ` Heiko Stuebner
2022-06-10  0:43 ` [PATCH 1/3] dt-bindings: riscv: document cbom-block-size Heiko Stuebner
2022-06-10  0:43   ` Heiko Stuebner
2022-06-17 20:37   ` Rob Herring
2022-06-17 20:37     ` Rob Herring
2022-06-10  0:43 ` [PATCH 2/3] riscv: Implement Zicbom-based cache management operations Heiko Stuebner
2022-06-10  0:43   ` Heiko Stuebner
2022-06-10  3:22   ` Randy Dunlap
2022-06-10  3:22     ` Randy Dunlap
2022-06-10  5:56   ` Christoph Hellwig
2022-06-10  5:56     ` Christoph Hellwig
2022-06-15 16:56     ` Heiko Stübner
2022-06-15 16:56       ` Heiko Stübner
2022-06-15 17:49       ` Christoph Hellwig
2022-06-15 17:49         ` Christoph Hellwig
2022-06-16  9:46         ` Heiko Stübner
2022-06-16  9:46           ` Heiko Stübner
2022-06-16 11:53           ` Christoph Hellwig
2022-06-16 11:53             ` Christoph Hellwig
2022-06-16 12:09             ` Heiko Stübner
2022-06-16 12:09               ` Heiko Stübner
2022-06-16 12:11               ` Christoph Hellwig [this message]
2022-06-16 12:11                 ` Christoph Hellwig
2022-06-17  8:30                 ` Heiko Stübner
2022-06-17  8:30                   ` Heiko Stübner
2022-06-12 19:15   ` Samuel Holland
2022-06-12 19:15     ` Samuel Holland
2022-06-13  5:50     ` Christoph Hellwig
2022-06-13  5:50       ` Christoph Hellwig
2022-06-10  0:43 ` [PATCH 3/3] riscv: implement cache-management errata for T-Head SoCs Heiko Stuebner
2022-06-10  0:43   ` Heiko Stuebner
2022-06-10  1:04   ` Guo Ren
2022-06-10  1:04     ` Guo Ren
2022-06-12 19:18   ` Samuel Holland
2022-06-12 19:18     ` Samuel Holland

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