From: Christoph Hellwig <hch@lst.de>
To: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Christoph Hellwig <hch@lst.de>,
linux-mips@vger.kernel.org, chenhc@lemote.com,
paul.burton@mips.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] MIPS: Define pgprot_dmacoherent according to coherentio status
Date: Mon, 13 Jan 2020 16:12:53 +0100 [thread overview]
Message-ID: <20200113151253.GA10064@lst.de> (raw)
In-Reply-To: <6A037EB9-B5FE-462F-A6EA-8FD874432E75@flygoat.com>
On Mon, Jan 13, 2020 at 11:11:58PM +0800, Jiaxun Yang wrote:
>
>
> 于 2020年1月13日 GMT+08:00 下午10:58:20, Christoph Hellwig <hch@lst.de> 写到:
> >On Mon, Jan 13, 2020 at 10:07:04PM +0800, Jiaxun Yang wrote:
> >> For MIPS chips that support coherentio DMA, it's always safe
> >> to make DMA requests cached.
> >
> >For DMA coherent devices pgprot_dmacoherent isn't even used, so this
> >doesn't make sense.
>
> Hi,
>
> I'm supposed to use it later in drm/ttm
> ttm_bo_util to overwrite pgprot for TTM_PL_SYSTEM.
> And I wish this pgropt can always represent dmacoherent pgropt.
> Would it be fine?
No code outside the core DMA code has any business using
pgprot_dmacoherent.
prev parent reply other threads:[~2020-01-13 15:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 14:07 [PATCH 1/2] MIPS: Define pgprot_dmacoherent according to coherentio status Jiaxun Yang
2020-01-13 14:07 ` [PATCH 2/2] MIPS: Loongson64: Add dma iocoherency detection support Jiaxun Yang
2020-01-13 18:52 ` Paul Burton
2020-01-14 3:30 ` Jiaxun Yang
2020-01-13 14:58 ` [PATCH 1/2] MIPS: Define pgprot_dmacoherent according to coherentio status Christoph Hellwig
2020-01-13 15:11 ` Jiaxun Yang
2020-01-13 15:12 ` Christoph Hellwig [this message]
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