Re: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings - Russell King

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From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org, linux-mm@kvack.org,
	linaro-mm-sig@lists.linaro.org,
	Michal Nazarewicz <mina86@mina86.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Ankita Garg <ankita@in.ibm.com>,
	Daniel Walker <dwalker@codeaurora.org>,
	Mel Gorman <mel@csn.ul.ie>,
	Jesse Barker <jesse.barker@linaro.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Shariq Hasnain <shariq.hasnain@linaro.org>,
	Chunsang Jeong <chunsang.jeong@linaro.org>
Subject: Re: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings
Date: Sun, 14 Aug 2011 08:52:05 +0100	[thread overview]
Message-ID: <20110814075205.GA4986@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <201108121453.05898.arnd@arndb.de>

On Fri, Aug 12, 2011 at 02:53:05PM +0200, Arnd Bergmann wrote:
> On Friday 12 August 2011, Marek Szyprowski wrote:
> > 
> > From: Russell King <rmk+kernel@arm.linux.org.uk>
> > 
> > Steal memory from the kernel to provide coherent DMA memory to drivers.
> > This avoids the problem with multiple mappings with differing attributes
> > on later CPUs.
> > 
> > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> > [m.szyprowski: rebased onto 3.1-rc1]
> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> 
> Hi Marek,
> 
> Is this the same patch that Russell had to revert because it didn't
> work on some of the older machines, in particular those using
> dmabounce?
> 
> I thought that our discussion ended with the plan to use this only
> for ARMv6+ (which has a problem with double mapping) but not on ARMv5
> and below (which don't have this problem but might need dmabounce).

I thought we'd decided to have a pool of available CMA memory on ARMv6K
to satisfy atomic allocations, which can grow and shrink in size, rather
than setting aside a fixed amount of contiguous system memory.

ARMv6 and ARMv7+ could use CMA directly, and <= ARMv5 can use the existing
allocation method.

Has something changed?

WARNING: multiple messages have this Message-ID (diff)

From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org, linux-mm@kvack.org,
	linaro-mm-sig@lists.linaro.org,
	Michal Nazarewicz <mina86@mina86.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Ankita Garg <ankita@in.ibm.com>,
	Daniel Walker <dwalker@codeaurora.org>,
	Mel Gorman <mel@csn.ul.ie>,
	Jesse Barker <jesse.barker@linaro.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Shariq Hasnain <shariq.hasnain@linaro.org>,
	Chunsang Jeong <chunsang.jeong@linaro.org>
Subject: Re: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings
Date: Sun, 14 Aug 2011 08:52:05 +0100	[thread overview]
Message-ID: <20110814075205.GA4986@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <201108121453.05898.arnd@arndb.de>

On Fri, Aug 12, 2011 at 02:53:05PM +0200, Arnd Bergmann wrote:
> On Friday 12 August 2011, Marek Szyprowski wrote:
> > 
> > From: Russell King <rmk+kernel@arm.linux.org.uk>
> > 
> > Steal memory from the kernel to provide coherent DMA memory to drivers.
> > This avoids the problem with multiple mappings with differing attributes
> > on later CPUs.
> > 
> > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> > [m.szyprowski: rebased onto 3.1-rc1]
> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> 
> Hi Marek,
> 
> Is this the same patch that Russell had to revert because it didn't
> work on some of the older machines, in particular those using
> dmabounce?
> 
> I thought that our discussion ended with the plan to use this only
> for ARMv6+ (which has a problem with double mapping) but not on ARMv5
> and below (which don't have this problem but might need dmabounce).

I thought we'd decided to have a pool of available CMA memory on ARMv6K
to satisfy atomic allocations, which can grow and shrink in size, rather
than setting aside a fixed amount of contiguous system memory.

ARMv6 and ARMv7+ could use CMA directly, and <= ARMv5 can use the existing
allocation method.

Has something changed?

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WARNING: multiple messages have this Message-ID (diff)

From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings
Date: Sun, 14 Aug 2011 08:52:05 +0100	[thread overview]
Message-ID: <20110814075205.GA4986@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <201108121453.05898.arnd@arndb.de>

On Fri, Aug 12, 2011 at 02:53:05PM +0200, Arnd Bergmann wrote:
> On Friday 12 August 2011, Marek Szyprowski wrote:
> > 
> > From: Russell King <rmk+kernel@arm.linux.org.uk>
> > 
> > Steal memory from the kernel to provide coherent DMA memory to drivers.
> > This avoids the problem with multiple mappings with differing attributes
> > on later CPUs.
> > 
> > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> > [m.szyprowski: rebased onto 3.1-rc1]
> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> 
> Hi Marek,
> 
> Is this the same patch that Russell had to revert because it didn't
> work on some of the older machines, in particular those using
> dmabounce?
> 
> I thought that our discussion ended with the plan to use this only
> for ARMv6+ (which has a problem with double mapping) but not on ARMv5
> and below (which don't have this problem but might need dmabounce).

I thought we'd decided to have a pool of available CMA memory on ARMv6K
to satisfy atomic allocations, which can grow and shrink in size, rather
than setting aside a fixed amount of contiguous system memory.

ARMv6 and ARMv7+ could use CMA directly, and <= ARMv5 can use the existing
allocation method.

Has something changed?

next prev parent reply	other threads:[~2011-08-14  7:52 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-12 10:58 [PATCHv14 0/9] Contiguous Memory Allocator Marek Szyprowski
2011-08-12 10:58 ` Marek Szyprowski
2011-08-12 10:58 ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 1/9] mm: move some functions from memory_hotplug.c to page_isolation.c Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 2/9] mm: alloc_contig_freed_pages() added Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 3/9] mm: alloc_contig_range() added Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 4/9] mm: MIGRATE_CMA migration type added Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 5/9] mm: MIGRATE_CMA isolation functions added Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 6/9] drivers: add Contiguous Memory Allocator Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 12:53   ` Arnd Bergmann
2011-08-12 12:53     ` Arnd Bergmann
2011-08-12 12:53     ` Arnd Bergmann
2011-08-14  7:52     ` Russell King - ARM Linux [this message]
2011-08-14  7:52       ` Russell King - ARM Linux
2011-08-14  7:52       ` Russell King - ARM Linux
2011-08-16 13:28       ` Arnd Bergmann
2011-08-16 13:28         ` Arnd Bergmann
2011-08-16 13:28         ` Arnd Bergmann
2011-08-16 13:55         ` Russell King - ARM Linux
2011-08-16 13:55           ` Russell King - ARM Linux
2011-08-16 13:55           ` Russell King - ARM Linux
2011-08-16 14:26           ` Arnd Bergmann
2011-08-16 14:26             ` Arnd Bergmann
2011-08-16 14:26             ` Arnd Bergmann
2011-08-17  8:01             ` Marek Szyprowski
2011-08-17  8:01               ` Marek Szyprowski
2011-08-17  8:01               ` Marek Szyprowski
2011-08-17 12:28               ` Arnd Bergmann
2011-08-17 12:28                 ` Arnd Bergmann
2011-08-17 12:28                 ` Arnd Bergmann
2011-08-17 13:06                 ` Marek Szyprowski
2011-08-17 13:06                   ` Marek Szyprowski
2011-08-17 13:06                   ` Marek Szyprowski
2011-08-18  8:27                   ` Tixy
2011-08-18  8:27                     ` Tixy
2011-08-18  8:27                     ` Tixy
2011-08-17 12:49             ` Marek Szyprowski
2011-08-17 12:49               ` Marek Szyprowski
2011-08-17 12:49               ` Marek Szyprowski
2011-08-16 10:17     ` Marek Szyprowski
2011-08-16 10:17       ` Marek Szyprowski
2011-08-16 10:17       ` Marek Szyprowski
2011-08-12 10:58 ` [PATCH 8/9] ARM: integrate CMA with DMA-mapping subsystem Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 15:00   ` Arnd Bergmann
2011-08-12 15:00     ` Arnd Bergmann
2011-08-12 15:00     ` Arnd Bergmann
2011-08-16  9:29     ` Marek Szyprowski
2011-08-16  9:29       ` Marek Szyprowski
2011-08-16  9:29       ` Marek Szyprowski
2011-08-16 13:14       ` Arnd Bergmann
2011-08-16 13:14         ` Arnd Bergmann
2011-08-16 13:14         ` Arnd Bergmann
2011-08-12 10:58 ` [PATCH 9/9] ARM: S5PV210: example of CMA private area for FIMC device on Goni board Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski
2011-08-12 10:58   ` Marek Szyprowski

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