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iommu/arm-smmu-v3: limit use of 2-level stream tables 

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 <nwatters@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Nate Watterson 2017-01-10 14:47:13 -05:00 committed by Will Deacon
parent 810871c570
commit 692c4e422d
1 changed files with 10 additions and 11 deletions
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21
drivers/iommu/arm-smmu-v3.c
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@ -1977,17 +1977,9 @@ 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;
@ -2498,6 +2490,13 @@ 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);