msm: iommu: Don't flush page tables if no devices attached

Don't flush the page tables on an IOMMU domain if there are
no IOMMU devices attached to the domain. The act of
attaching to the domain will cause an implicit flush of
those areas if the page tables are configured to not be L2
cacheable.

Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Daniel Walker <dwalker@codeaurora.org>

1 files changed, 9 insertions, 6 deletions

diff --git a/arch/arm/mach-msm/iommu.c b/arch/arm/mach-msm/iommu.c
index 134add789187..74f2157eba4e 100644
--- a/arch/arm/mach-msm/iommu.c
+++ b/arch/arm/mach-msm/iommu.c
@@ -50,13 +50,16 @@ static void __flush_iotlb(struct iommu_domain *domain)
         unsigned long *fl_table = priv->pgtable;
         int i;
 
-        dmac_flush_range(fl_table, fl_table + SZ_16K);
+        if (!list_empty(&priv->list_attached)) {
+                dmac_flush_range(fl_table, fl_table + SZ_16K);
 
-        for (i = 0; i < NUM_FL_PTE; i++)
-                if ((fl_table[i] & 0x03) == FL_TYPE_TABLE) {
-                        void *sl_table = __va(fl_table[i] & FL_BASE_MASK);
-                        dmac_flush_range(sl_table, sl_table + SZ_4K);
-                }
+                for (i = 0; i < NUM_FL_PTE; i++)
+                        if ((fl_table[i] & 0x03) == FL_TYPE_TABLE) {
+                                void *sl_table = __va(fl_table[i] &
+                                                                FL_BASE_MASK);
+                                dmac_flush_range(sl_table, sl_table + SZ_4K);
+                        }
+        }
 #endif
 
         list_for_each_entry(ctx_drvdata, &priv->list_attached, attached_elm) {