From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: JABLONSKY Jan <Jan.JABLONSKY@thalesgroup.com>
Cc: Chris Cole <chris@sageembedded.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: arm: dma-mapping: CPU may not see up-to-date data after DMA transaction
Date: Tue, 8 Jan 2019 09:51:33 +0000 [thread overview]
Message-ID: <20190108095133.GP11171@n2100.armlinux.org.uk> (raw)
In-Reply-To: <1546927833.511.68.camel@atviedlbe741.rss.d3s.at.thales>
On Tue, Jan 08, 2019 at 06:10:33AM +0000, JABLONSKY Jan wrote:
> Hi again,
>
> I saw, that there are some findings in v7_dma_inv_range
> https://patchwork.kernel.org/patch/10673097/
>
>
> It wouldn't be better to replace it directly with C&I ?
No.
> Otherwise still there is risk that you lost writes in->out ?
> (Exactly happens in my case)
For a region that is being used to DMA data _from_ the device, the
data we have in the cache need not be written back out except if
there are overlapping cache lines - writing it out would be a
complete waste of bus bandwidth.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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prev parent reply other threads:[~2019-01-08 9:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 7:36 arm: dma-mapping: CPU may not see up-to-date data after DMA transaction JABLONSKY Jan
2018-11-22 9:29 ` Russell King - ARM Linux
2018-11-22 12:25 ` JABLONSKY Jan
2018-11-22 12:51 ` Russell King - ARM Linux
2018-11-22 15:36 ` JABLONSKY Jan
2018-11-22 16:36 ` Robin Murphy
2018-11-22 16:57 ` Russell King - ARM Linux
2019-01-08 6:10 ` JABLONSKY Jan
2019-01-08 9:51 ` Russell King - ARM Linux [this message]
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