From: Maxim Kochetkov <fido_max@inbox.ru>
To: Christoph Hellwig <hch@lst.de>, Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Conor Dooley <conor@kernel.org>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
robh@kernel.org, mpe@ellerman.id.au, aou@eecs.berkeley.edu,
palmer@dabbelt.com, paul.walmsley@sifive.com
Subject: Re: [PATCH 1/1] riscv: set ARCH_DMA_DEFAULT_COHERENT if RISCV_DMA_NONCOHERENT is not set
Date: Mon, 25 Dec 2023 09:47:21 +0300 [thread overview]
Message-ID: <15b89089-3dcd-4668-8d8b-d12ff0684c29@inbox.ru> (raw)
In-Reply-To: <20231223045912.GA21836@lst.de>
On 23.12.2023 07:59, Christoph Hellwig wrote:
> On Fri, Dec 22, 2023 at 04:01:43PM +0000, Jiaxun Yang wrote:
>>>
>>> But arch_setup_dma_ops() is called only from of_dma_configure_id() and
>>> acpi_dma_configure_id(). So it works only for DT and ACPI devices. What
>>> about platform_device?
>>
>> Ah I see, that's the problem, in MIPS's use case all DMA capable devices
>> are following platform's default coherency. For RISC-V we assume all device
>> are enabled by ACPI or DT.
>>
>> Perhaps you can override it in driver, but that will make drivers platform
>> dependent.
>>
>> I'll leave this question to Christoph.
>
> I've already said it. You must not have DMA capable devices that aren't
> declared in ACPI or OF, just like on any modern Linux platform.
Ok. I've got the point. Thank you for clarification.
>
> What devices are you concerned about anyway Maxim?
I have 3rd party external out of tree camera driver. csi, isp, dewarp
components are OF, but common media device is created as
platform_device. I will convert is to OF.
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prev parent reply other threads:[~2023-12-25 6:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-21 18:51 [PATCH 1/1] riscv: set ARCH_DMA_DEFAULT_COHERENT if RISCV_DMA_NONCOHERENT is not set Maxim Kochetkov
2023-12-21 20:29 ` Conor Dooley
2023-12-21 22:27 ` Jiaxun Yang
2023-12-22 4:14 ` Christoph Hellwig
2023-12-22 14:39 ` Maxim Kochetkov
2023-12-22 14:54 ` Conor Dooley
2023-12-22 15:04 ` Christoph Hellwig
2023-12-22 15:38 ` Maxim Kochetkov
2023-12-22 15:45 ` Jiaxun Yang
2023-12-22 15:53 ` Maxim Kochetkov
2023-12-22 16:01 ` Jiaxun Yang
2023-12-23 4:59 ` Christoph Hellwig
2023-12-25 6:47 ` Maxim Kochetkov [this message]
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