In the current arm-smmu-v3 driver, all smmus that support 2-level
stream tables are being forced to use them. This is suboptimal for
smmus that support fewer stream id bits than would fill in a single
second level table. This patch limits the use of 2-level tables to
smmus that both support the feature and whose first level table can
possibly contain more than a single entry.
Signed-off-by: Nate Watterson <nwatt...@codeaurora.org>
---
drivers/iommu/arm-smmu-v3.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4d6ec44..7d1a7e5 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1983,17 +1983,9 @@ static int arm_smmu_init_strtab_2lvl(struct
arm_smmu_device *smmu)
u32 size, l1size;
struct arm_smmu_strtab_cfg *cfg = &smmu->strtab_cfg;
- /*
- * If we can resolve everything with a single L2 table, then we
- * just need a single L1 descriptor. Otherwise, calculate the L1
- * size, capped to the SIDSIZE.
- */
- if (smmu->sid_bits < STRTAB_SPLIT) {
- size = 0;
- } else {
- size = STRTAB_L1_SZ_SHIFT - (ilog2(STRTAB_L1_DESC_DWORDS) + 3);
- size = min(size, smmu->sid_bits - STRTAB_SPLIT);
- }
+ /* Calculate the L1 size, capped to the SIDSIZE. */
+ size = STRTAB_L1_SZ_SHIFT - (ilog2(STRTAB_L1_DESC_DWORDS) + 3);
+ size = min(size, smmu->sid_bits - STRTAB_SPLIT);
cfg->num_l1_ents = 1 << size;
size += STRTAB_SPLIT;
@@ -2504,6 +2496,13 @@ static int arm_smmu_device_hw_probe(struct
arm_smmu_device *smmu)
smmu->ssid_bits = reg >> IDR1_SSID_SHIFT & IDR1_SSID_MASK;
smmu->sid_bits = reg >> IDR1_SID_SHIFT & IDR1_SID_MASK;
+ /*
+ * If the SMMU supports fewer bits than would fill a single L2 stream
+ * table, use a linear table instead.
+ */
+ if (smmu->sid_bits <= STRTAB_SPLIT)
+ smmu->features &= ~ARM_SMMU_FEAT_2_LVL_STRTAB;
+
/* IDR5 */
reg = readl_relaxed(smmu->base + ARM_SMMU_IDR5);
--
Qualcomm Datacenter Technologies, Inc. on behalf of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
Foundation Collaborative Project.
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