From: Sascha Hauer <s.hauer@pengutronix.de>
To: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] ARM: mmu64: Don't flush freshly invalidated region
Date: Fri, 24 Aug 2018 10:12:21 +0200 [thread overview]
Message-ID: <20180824081221.sfbshtbnlbeas5aa@pengutronix.de> (raw)
In-Reply-To: <20180824025421.19968-1-andrew.smirnov@gmail.com>
On Thu, Aug 23, 2018 at 07:54:21PM -0700, Andrey Smirnov wrote:
> Current code for dma_sync_single_for_device(), when called with dir
> set to DMA_FROM_DEVICE, will first invalidate given region of memory
> as a first step and then clean+invalidate it as a second. While the
> second step should be harmless it seems to be an unnecessary no-op
> that could probably be avoided.
>
> Analogous code in Linux kernel (4.18) in arch/arm64/mm/cache.S:
>
> ENTRY(__dma_map_area)
> cmp w2, #DMA_FROM_DEVICE
> b.eq __dma_inv_area
> b __dma_clean_area
> ENDPIPROC(__dma_map_area)
>
> is written to only perform either invalidate or clean, depending on
> the direction, so change dma_sync_single_for_device() to behave in the
> same vein and perfom _either_ invlidate or flush of the given region.
>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
Applied, thanks
Sascha
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prev parent reply other threads:[~2018-08-24 8:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-24 2:54 Andrey Smirnov
2018-08-24 8:12 ` Sascha Hauer [this message]
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