On 8/2/13 12:34 AM, "Brice Goglin" <brice.gog...@inria.fr> wrote:
>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.gog...@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; Actually we can delete this now because is_xeon_cb32() already effectively means that raid offload will not be used. > > 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 */ > I like Jon¹s suggestion. Just make raid disabled by default on non-atom platforms. When if a non-atom platform comes along without the previous restrictions it can add itself to this list. So let¹s drop the module parameter and just cleanup the 3.2 support to reflect the current reality of raid being disabled. -- Dan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
