linux-kernel - Re: [PATCH 2/2] arm: mvebu: Add hardware I/O Coherency support

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Date:	Wed, 24 Oct 2012 13:48:04 +0200
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	Jason Cooper <jason@...edaemon.net>, Andrew Lunn <andrew@...n.ch>,
	linux-arm-kernel@...ts.infradead.org,
	Olof Johansson <olof@...om.net>,
	Russell King <linux@....linux.org.uk>,
	Rob Herring <rob.herring@...xeda.com>,
	Ben Dooks <ben-linux@...ff.org>,
	Ian Molton <ian.molton@...ethink.co.uk>,
	Nicolas Pitre <nico@...xnic.net>,
	Lior Amsalem <alior@...vell.com>,
	Maen Suleiman <maen@...vell.com>,
	Tawfik Bayouk <tawfik@...vell.com>,
	Shadi Ammouri <shadi@...vell.com>,
	Eran Ben-Avi <benavi@...vell.com>,
	Yehuda Yitschak <yehuday@...vell.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Ike Pan <ike.pan@...onical.com>,
	Jani Monoses <jani.monoses@...onical.com>,
	Chris Van Hoof <vanhoof@...onical.com>,
	Dan Frazier <dann.frazier@...onical.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Leif Lindholm <leif.lindholm@....com>,
	Jon Masters <jcm@...hat.com>,
	David Marlin <dmarlin@...hat.com>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] arm: mvebu: Add hardware I/O Coherency support

On 10/24/2012 01:36 PM, Arnd Bergmann wrote:
> On Wednesday 24 October 2012, Gregory CLEMENT wrote:
>> +void __init armada_370_xp_coherency_iocache_init(void)
>> +{
>> +       /* When the coherency fabric is available, the Armada XP and
>> +        * Aramada 370 are close to a coherent architecture, so we based
>> +        * our dma ops on the coherent one, and just changes the
>> +        * operations which need a arch io sync */
>> +       if (of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric")) {
>> +               struct dma_map_ops *dma_ops = &armada_xp_dma_ops;
>> +               memcpy(dma_ops, &arm_coherent_dma_ops, sizeof(*dma_ops));
>> +               dma_ops->map_page = armada_xp_dma_map_page;
>> +               dma_ops->unmap_page = armada_xp_dma_unmap_page;
>> +               dma_ops->unmap_sg = arm_dma_ops.unmap_sg;
>> +               dma_ops->sync_single_for_cpu = armada_xp_dma_sync;
>> +               dma_ops->sync_single_for_device = armada_xp_dma_sync;
>> +               dma_ops->sync_sg_for_cpu = arm_dma_ops.sync_sg_for_cpu;
>> +               dma_ops->sync_sg_for_device = arm_dma_ops.sync_sg_for_device;
>> +       }
>> +       bus_register_notifier(&platform_bus_type, &armada_xp_platform_nb);
> 
> I think it would be cleaner to statically define the operations in a constant
> structure and point directly to the functions you need. If necessary, use
> multiple structures.

My problem was that these functions are not exposed, only arm_dma_op and
arm_coherent_dma_ops are exported.
Or do you think about something like this:

struct dma_map_ops *dma_ops = {
	.alloc			= arm_dma_ops.arm_coherent_dma_alloc,
	.free			= arm_dma_ops.arm_coherent_dma_free,
	.mmap			= arm_dma_ops.arm_dma_mmap,
	.get_sgtable		= arm_dma_ops.arm_dma_get_sgtable,
	.map_sg			= arm_dma_ops.arm_dma_map_sg,
	.set_dma_mask		= arm_dma_ops.arm_dma_set_mask,
	.map_page 		= armada_xp_dma_map_page,
	.unmap_page 		= armada_xp_dma_unmap_page,
	.unmap_sg 		= arm_dma_ops.unmap_sg,
	.sync_single_for_cpu 	= armada_xp_dma_sync,
	.sync_single_for_device = armada_xp_dma_sync,
	.sync_sg_for_cpu 	= arm_dma_ops.sync_sg_for_cpu,
	.sync_sg_for_device	= arm_dma_ops.sync_sg_for_device,
};




> 
> 	Arnd
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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