Patch "iommu/tegra-smmu: Parameterize number of TLB lines" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    iommu/tegra-smmu: Parameterize number of TLB lines

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iommu-tegra-smmu-parameterize-number-of-tlb-lines.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 11cec15bf3fb498206ef63b1fa26c27689e02d0e Mon Sep 17 00:00:00 2001
From: Thierry Reding <treding@nvidia.com>
Date: Thu, 6 Aug 2015 14:20:31 +0200
Subject: iommu/tegra-smmu: Parameterize number of TLB lines

From: Thierry Reding <treding@nvidia.com>

commit 11cec15bf3fb498206ef63b1fa26c27689e02d0e upstream.

The number of TLB lines was increased from 16 on Tegra30 to 32 on
Tegra114 and later. Parameterize the value so that the initial default
can be set accordingly.

On Tegra30, initializing the value to 32 would effectively disable the
TLB and hence cause massive latencies for memory accesses translated
through the SMMU. This is especially noticeable for isochronuous clients
such as display, whose FIFOs would continuously underrun.

Fixes: 891846516317 ("memory: Add NVIDIA Tegra memory controller support")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iommu/tegra-smmu.c      |    9 +++++++--
 drivers/memory/tegra/tegra114.c |    1 +
 drivers/memory/tegra/tegra124.c |    1 +
 drivers/memory/tegra/tegra30.c  |    1 +
 include/soc/tegra/mc.h          |    1 +
 5 files changed, 11 insertions(+), 2 deletions(-)

--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -27,6 +27,7 @@ struct tegra_smmu {
 	const struct tegra_smmu_soc *soc;
 
 	unsigned long pfn_mask;
+	unsigned long tlb_mask;
 
 	unsigned long *asids;
 	struct mutex lock;
@@ -68,7 +69,8 @@ static inline u32 smmu_readl(struct tegr
 #define SMMU_TLB_CONFIG 0x14
 #define  SMMU_TLB_CONFIG_HIT_UNDER_MISS (1 << 29)
 #define  SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION (1 << 28)
-#define  SMMU_TLB_CONFIG_ACTIVE_LINES(x) ((x) & 0x3f)
+#define  SMMU_TLB_CONFIG_ACTIVE_LINES(smmu) \
+	((smmu)->soc->num_tlb_lines & (smmu)->tlb_mask)
 
 #define SMMU_PTC_CONFIG 0x18
 #define  SMMU_PTC_CONFIG_ENABLE (1 << 29)
@@ -816,6 +818,9 @@ struct tegra_smmu *tegra_smmu_probe(stru
 	smmu->pfn_mask = BIT_MASK(mc->soc->num_address_bits - PAGE_SHIFT) - 1;
 	dev_dbg(dev, "address bits: %u, PFN mask: %#lx\n",
 		mc->soc->num_address_bits, smmu->pfn_mask);
+	smmu->tlb_mask = (smmu->soc->num_tlb_lines << 1) - 1;
+	dev_dbg(dev, "TLB lines: %u, mask: %#lx\n", smmu->soc->num_tlb_lines,
+		smmu->tlb_mask);
 
 	value = SMMU_PTC_CONFIG_ENABLE | SMMU_PTC_CONFIG_INDEX_MAP(0x3f);
 
@@ -825,7 +830,7 @@ struct tegra_smmu *tegra_smmu_probe(stru
 	smmu_writel(smmu, value, SMMU_PTC_CONFIG);
 
 	value = SMMU_TLB_CONFIG_HIT_UNDER_MISS |
-		SMMU_TLB_CONFIG_ACTIVE_LINES(0x20);
+		SMMU_TLB_CONFIG_ACTIVE_LINES(smmu);
 
 	if (soc->supports_round_robin_arbitration)
 		value |= SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION;
--- a/drivers/memory/tegra/tegra114.c
+++ b/drivers/memory/tegra/tegra114.c
@@ -935,6 +935,7 @@ static const struct tegra_smmu_soc tegra
 	.num_swgroups = ARRAY_SIZE(tegra114_swgroups),
 	.supports_round_robin_arbitration = false,
 	.supports_request_limit = false,
+	.num_tlb_lines = 32,
 	.num_asids = 4,
 	.ops = &tegra114_smmu_ops,
 };
--- a/drivers/memory/tegra/tegra124.c
+++ b/drivers/memory/tegra/tegra124.c
@@ -1023,6 +1023,7 @@ static const struct tegra_smmu_soc tegra
 	.num_swgroups = ARRAY_SIZE(tegra124_swgroups),
 	.supports_round_robin_arbitration = true,
 	.supports_request_limit = true,
+	.num_tlb_lines = 32,
 	.num_asids = 128,
 	.ops = &tegra124_smmu_ops,
 };
--- a/drivers/memory/tegra/tegra30.c
+++ b/drivers/memory/tegra/tegra30.c
@@ -957,6 +957,7 @@ static const struct tegra_smmu_soc tegra
 	.num_swgroups = ARRAY_SIZE(tegra30_swgroups),
 	.supports_round_robin_arbitration = false,
 	.supports_request_limit = false,
+	.num_tlb_lines = 16,
 	.num_asids = 4,
 	.ops = &tegra30_smmu_ops,
 };
--- a/include/soc/tegra/mc.h
+++ b/include/soc/tegra/mc.h
@@ -66,6 +66,7 @@ struct tegra_smmu_soc {
 	bool supports_round_robin_arbitration;
 	bool supports_request_limit;
 
+	unsigned int num_tlb_lines;
 	unsigned int num_asids;
 
 	const struct tegra_smmu_ops *ops;


Patches currently in stable-queue which might be from treding@nvidia.com are

queue-4.2/iommu-tegra-smmu-parameterize-number-of-tlb-lines.patch