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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2014-11-13 10:38:57 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-16 06:59:02 -0800
commitf35fff85dc8a8ee4fea7802d44822d1f18d035ed (patch)
treef358da17b90e8c88f1dbb67e88eee61c2caa42f4 /fs
parent697f52b45551255d3e151110cba150107141de56 (diff)
ARM: mvebu: disable I/O coherency on non-SMP situations on Armada 370/375/38x/XP
commit e55355453600a33bb5ca4f71f2d7214875f3b061 upstream. Enabling the hardware I/O coherency on Armada 370, Armada 375, Armada 38x and Armada XP requires a certain number of conditions: - On Armada 370, the cache policy must be set to write-allocate. - On Armada 375, 38x and XP, the cache policy must be set to write-allocate, the pages must be mapped with the shareable attribute, and the SMP bit must be set Currently, on Armada XP, when CONFIG_SMP is enabled, those conditions are met. However, when Armada XP is used in a !CONFIG_SMP kernel, none of these conditions are met. With Armada 370, the situation is worse: since the processor is single core, regardless of whether CONFIG_SMP or !CONFIG_SMP is used, the cache policy will be set to write-back by the kernel and not write-allocate. Since solving this problem turns out to be quite complicated, and we don't want to let users with a mainline kernel known to have infrequent but existing data corruptions, this commit proposes to simply disable hardware I/O coherency in situations where it is known not to work. And basically, the is_smp() function of the kernel tells us whether it is OK to enable hardware I/O coherency or not, so this commit slightly refactors the coherency_type() function to return COHERENCY_FABRIC_TYPE_NONE when is_smp() is false, or the appropriate type of the coherency fabric in the other case. Thanks to this, the I/O coherency fabric will no longer be used at all in !CONFIG_SMP configurations. It will continue to be used in CONFIG_SMP configurations on Armada XP, Armada 375 and Armada 38x (which are multiple cores processors), but will no longer be used on Armada 370 (which is a single core processor). In the process, it simplifies the implementation of the coherency_type() function, and adds a missing call to of_node_put(). Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Fixes: e60304f8cb7bb545e79fe62d9b9762460c254ec2 ("arm: mvebu: Add hardware I/O Coherency support") Cc: <stable@vger.kernel.org> # v3.8+ Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com> Link: https://lkml.kernel.org/r/1415871540-20302-3-git-send-email-thomas.petazzoni@free-electrons.com Signed-off-by: Jason Cooper <jason@lakedaemon.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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