Hi Laurent,
On 03/07/2014 06:46 PM, Laurent Pinchart wrote:
The flush_iotlb_page() function prints a debug message when no
corresponding page was found in the TLB. That condition is incorrectly
checked and always resolves to true, given that the for_each_iotlb_cr()
loop is never interrupted and always reaches obj->nr_tlb_entries.
Nice catch.
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
drivers/iommu/omap-iommu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index bb605c9..cb1e1de 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -376,6 +376,7 @@ static void flush_iotlb_page(struct omap_iommu *obj, u32 da)
{
int i;
struct cr_regs cr;
+ bool found = false;
pm_runtime_get_sync(obj->dev);
@@ -394,11 +395,12 @@ static void flush_iotlb_page(struct omap_iommu *obj, u32 da)
__func__, start, da, bytes);
iotlb_load_cr(obj, &cr);
iommu_write_reg(obj, 1, MMU_FLUSH_ENTRY);
+ found = true;
The patch is fine as it is, but I think the loop can be breaked when an
entry is found for simplification. I do not expect that we will have
multiple entries with the same da in the TLBs (it is a multi-hit fault
scenario) to continue looping through all entries. The only means for
the multi-hit scenario to happen is user error with programming TLBs
directly. This function call seems to be added in general to take care
of any prefetching. I don't have the complete history on the
PREFETCH_IOTLB on why it was added, it doesn't seem to be enabled but
this should ideally be left to the h/w unless you are locking a TLB
entry. DSP/Bridge is the only one that uses locked TLB entries at the
moment, but it is not using the OMAP IOMMU driver yet.
regards
Suman
}
}
pm_runtime_put_sync(obj->dev);
- if (i == obj->nr_tlb_entries)
+ if (!found)
dev_dbg(obj->dev, "%s: no page for %08x\n", __func__, da);
}
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