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From: Rob Herring <robh+dt@kernel.org>
To: Atish Patra <atish.patra@wdc.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Albert Ou <aou@eecs.berkeley.edu>, Christoph Hellwig <hch@lst.de>,
	devicetree@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>,
	Frank Rowand <frowand.list@gmail.com>,
	Guo Ren <guoren@linux.alibaba.com>,
	Linux IOMMU <iommu@lists.linux-foundation.org>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Tobias Klauser <tklauser@distanz.ch>
Subject: Re: [RFC 3/5] dma-mapping: Enable global non-coherent pool support for RISC-V
Date: Sun, 25 Jul 2021 16:29:12 -0600	[thread overview]
Message-ID: <CAL_JsqKG9xkSAQGkBE8_BEE+O9S+z09M8C9+gWN-58aXEZWqgg@mail.gmail.com> (raw)
In-Reply-To: <20210723214031.3251801-4-atish.patra@wdc.com>

On Fri, Jul 23, 2021 at 3:40 PM Atish Patra <atish.patra@wdc.com> wrote:
>
> Currently, linux,dma-default is used to reserve a global non-coherent pool
> to allocate memory for dma operations. This can be useful for RISC-V as
> well as the ISA specification doesn't specify a method to modify PMA
> attributes or page table entries to define non-cacheable area yet.
> A non-cacheable memory window is an alternate options for vendors to
> support non-coherent devices. "dma-ranges" must be used in conjunction with
> "linux,dma-default" property to define one or more mappings between device
> and cpu accesible memory regions.

'dma-ranges' applies to buses. And, well, maybe devices when the bus
is not well defined. It is not a reserved-memory property.

Rob

  reply	other threads:[~2021-07-25 22:29 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 21:40 [RFC 0/5] Support non-coherent DMA on RISC-V using a global pool Atish Patra
2021-07-23 21:40 ` [RFC 1/5] RISC-V: Implement arch_sync_dma* functions Atish Patra
2021-07-26  6:56   ` Christoph Hellwig
2021-07-26 21:52     ` Atish Patra
2021-09-11  9:37       ` Guo Ren
2021-08-17  1:48   ` Guo Ren
2021-08-17  3:24     ` Atish Patra
2021-08-17  6:28       ` Guo Ren
2021-07-23 21:40 ` [RFC 2/5] of: Move of_dma_get_range to of_address.h Atish Patra
2021-07-23 21:40 ` [RFC 3/5] dma-mapping: Enable global non-coherent pool support for RISC-V Atish Patra
2021-07-25 22:29   ` Rob Herring [this message]
2021-07-26  7:00   ` Christoph Hellwig
2021-07-26 22:47     ` Atish Patra
2021-07-27  8:52       ` Christoph Hellwig
2021-08-02 18:22         ` Atish Patra
2021-07-23 21:40 ` [RFC 4/5] dma-direct: Allocate dma pages directly if global pool allocation fails Atish Patra
2021-07-26  7:01   ` Christoph Hellwig
2021-07-23 21:40 ` [RFC 5/5] RISC-V: Support a new config option for non-coherent DMA Atish Patra
2021-07-29  4:30 ` [RFC 0/5] Support non-coherent DMA on RISC-V using a global pool Palmer Dabbelt
2021-07-29  6:19   ` Atish Patra
2021-08-17  1:37     ` Guo Ren
2021-08-17  3:28       ` Atish Patra
2021-08-17  6:42         ` Guo Ren

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