[PATCH] arm: mm: add memory type for inner-writeback

Mark Zhang
2013-12-27T04:59:22Z

From: Colin Cross <ccross@android.com>

For streaming-style operations (e.g., software rendering of graphics
surfaces shared with non-coherent DMA devices), the cost of performing
L2 cache maintenance can exceed the benefit of having the larger cache
(this is particularly true for OUTER_CACHE configurations like the ARM
PL2x0).

This change uses the currently-unused mapping 5 (TEX[0]=1, C=0, B=1)
in the tex remapping tables as an inner-writeback-write-allocate, outer
non-cacheable memory type, so that this mapping will be available to
clients which will benefit from the reduced L2 maintenance.

Signed-off-by: Gary King <gking@nvidia.com>
---
arch/arm/include/asm/pgtable-2level.h | 1 +
arch/arm/include/asm/pgtable.h | 3 +++
arch/arm/mm/proc-macros.S | 2 +-
arch/arm/mm/proc-v7-2level.S | 4 ++--
arch/arm/mm/proc-xsc3.S | 2 +-
arch/arm/mm/proc-xscale.S | 2 +-
6 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index dfff709fda3c..528b397b6c91 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -141,6 +141,7 @@
#define L_PTE_MT_DEV_WC (_AT(pteval_t, 0x09) << 2) /* 1001 */
#define L_PTE_MT_DEV_CACHED (_AT(pteval_t, 0x0b) << 2) /* 1011 */
#define L_PTE_MT_MASK (_AT(pteval_t, 0x0f) << 2)
+#define L_PTE_MT_INNER_WB (_AT(pteval_t, 0x05) << 2) /* 0101 (armv6, armv7) */

#ifndef __ASSEMBLY__

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 7d59b524f2af..2b0601a9a18e 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -134,6 +134,9 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
__pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_UNCACHED | L_PTE_XN)
#endif

+#define pgprot_inner_writeback(prot) \
+ __pgprot_modify(prot, L_PTE_MT_MASK, L_PTE_MT_INNER_WB)
+
#endif /* __ASSEMBLY__ */

/*
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S
index e3c48a3fe063..fa829840ee16 100644
--- a/arch/arm/mm/proc-macros.S
+++ b/arch/arm/mm/proc-macros.S
@@ -127,7 +127,7 @@
.long PTE_CACHEABLE @ L_PTE_MT_WRITETHROUGH
.long PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_WRITEBACK
.long PTE_BUFFERABLE @ L_PTE_MT_DEV_SHARED
- .long 0x00 @ unused
+ .long PTE_EXT_TEX(4) | PTE_BUFFERABLE @ L_PTE_MT_INNER_WB
.long 0x00 @ L_PTE_MT_MINICACHE (not present)
.long PTE_EXT_TEX(1) | PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_WRITEALLOC
.long 0x00 @ unused
diff --git a/arch/arm/mm/proc-v7-2level.S b/arch/arm/mm/proc-v7-2level.S
index bdd3be4be77a..059a9d7242c2 100644
--- a/arch/arm/mm/proc-v7-2level.S
+++ b/arch/arm/mm/proc-v7-2level.S
@@ -144,8 +144,8 @@ ENDPROC(cpu_v7_set_pte_ext)
* NS1 = PRRR[19] = 1 - normal shareable property
* NOS = PRRR[24+n] = 1 - not outer shareable
*/
-.equ PRRR, 0xff0a81a8
-.equ NMRR, 0x40e040e0
+.equ PRRR, 0xff0a89a8
+.equ NMRR, 0x40e044e0

/*
* Macro for setting up the TTBRx and TTBCR registers.
diff --git a/arch/arm/mm/proc-xsc3.S b/arch/arm/mm/proc-xsc3.S
index dc1645890042..9c374495e778 100644
--- a/arch/arm/mm/proc-xsc3.S
+++ b/arch/arm/mm/proc-xsc3.S
@@ -381,7 +381,7 @@ cpu_xsc3_mt_table:
.long PTE_EXT_TEX(5) | PTE_CACHEABLE @ L_PTE_MT_WRITETHROUGH
.long PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_WRITEBACK
.long PTE_EXT_TEX(1) | PTE_BUFFERABLE @ L_PTE_MT_DEV_SHARED
- .long 0x00 @ unused
+ .long PTE_EXT_TEX(4) | PTE_BUFFERABLE @ L_PTE_MT_INNER_WB (not present?)
.long 0x00 @ L_PTE_MT_MINICACHE (not present)
.long PTE_EXT_TEX(5) | PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_WRITEALLOC (not present?)
.long 0x00 @ unused
diff --git a/arch/arm/mm/proc-xscale.S b/arch/arm/mm/proc-xscale.S
index d19b1cfcad91..2ac1b88e02ac 100644
--- a/arch/arm/mm/proc-xscale.S
+++ b/arch/arm/mm/proc-xscale.S
@@ -491,7 +491,7 @@ cpu_xscale_mt_table:
.long PTE_CACHEABLE @ L_PTE_MT_WRITETHROUGH
.long PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_WRITEBACK
.long PTE_EXT_TEX(1) | PTE_BUFFERABLE @ L_PTE_MT_DEV_SHARED
- .long 0x00 @ unused
+ .long PTE_EXT_TEX(1) | PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_INNER_WB
.long PTE_EXT_TEX(1) | PTE_CACHEABLE @ L_PTE_MT_MINICACHE
.long PTE_EXT_TEX(1) | PTE_CACHEABLE | PTE_BUFFERABLE @ L_PTE_MT_WRITEALLOC
.long 0x00 @ unused
--
1.8.1.5