Messages in this thread Patch in this message | | | Date | Fri, 02 Aug 2013 09:34:36 +0200 | From | Brice Goglin <> | Subject | Re: ioatdma: add ioat_raid_enabled module parameter |
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Le 01/08/2013 19:15, Jiang, Dave a écrit : > On Thu, 2013-08-01 at 10:11 -0700, Jon Mason wrote: >> On Wed, Jul 31, 2013 at 03:14:07PM -0700, Jiang, Dave wrote: >>> I'm ok with enabling this for people that just want to use DMA and not >>> RAID. >> I might be crazy, but I'd be in favor of disabling the RAID offload by >> default on non-Atom platforms. >> > I suppose. Technically it is disabled starting with 3.10 because of the > channel switch issue. I'm ok with this disabled by default for the 3.2 > platforms that has broken pq-val. >
Here's a patch that may do what you guys are saying.
Brice
ioatdma: disable RAID by default when buggy and add module param
Commit f26df1a1 added a 64-byte alignment requirement for legacy operations to work around a silicon errata when mixing legacy and RAID descriptors.
RAID offload is now disabled by default on buggy 3.2 platforms. Passing ioat_raid_enabled=1 force-enables it on all platforms (previous behavior). Passing ioat_raid_enabled=0 force-disables it everywhere.
When RAID offload is disabled, legacy operations (memcpy, etc.) can work again without alignment restrictions.
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr> --- drivers/dma/ioat/dma_v3.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
Index: b/drivers/dma/ioat/dma_v3.c =================================================================== --- a/drivers/dma/ioat/dma_v3.c 2013-07-31 23:06:24.163810000 +0200 +++ b/drivers/dma/ioat/dma_v3.c 2013-08-02 09:28:51.817037742 +0200 @@ -67,6 +67,11 @@ #include "dma.h" #include "dma_v2.h" +static int ioat_raid_enabled = -1; +module_param(ioat_raid_enabled, int, 0444); +MODULE_PARM_DESC(ioat_raid_enabled, + "control support of RAID offload (-1=enabled unless broken [default], 0=disabled, 1=enabled)"); + /* ioat hardware assumes at least two sources for raid operations */ #define src_cnt_to_sw(x) ((x) + 2) #define src_cnt_to_hw(x) ((x) - 2) @@ -1775,7 +1780,7 @@ int ioat3_dma_probe(struct ioatdma_devic dma->device_alloc_chan_resources = ioat2_alloc_chan_resources; dma->device_free_chan_resources = ioat2_free_chan_resources; - if (is_xeon_cb32(pdev)) + if (ioat_raid_enabled == 1 && is_xeon_cb32(pdev)) dma->copy_align = 6; dma_cap_set(DMA_INTERRUPT, dma->cap_mask); @@ -1783,7 +1788,14 @@ int ioat3_dma_probe(struct ioatdma_devic device->cap = readl(device->reg_base + IOAT_DMA_CAP_OFFSET); - if (is_bwd_noraid(pdev)) + /* disable RAID if: + * force-disabled by module param, + * or not force-enabled on buggy 3.2 platforms, + * or not actually supported. + */ + if (ioat_raid_enabled == 0 + || (ioat_raid_enabled != 1 && is_xeon_cb32(pdev)) + || is_bwd_noraid(pdev)) device->cap &= ~(IOAT_CAP_XOR | IOAT_CAP_PQ | IOAT_CAP_RAID16SS); /* dca is incompatible with raid operations */
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