Re: [U-Boot] [PATCH 2/6] omap: Set appropriate cache configuration for LPAE and non-LAPE cases

[Tom Rini]

On Wed, Sep 14, 2016 at 10:43:29AM +0530, Keerthy wrote:

> Cache configuration methods is different for LPAE and non-LPAE cases.
> Hence the bits and the interpretaion is different for two cases.
> In case of non-LPAE mode short descriptor format is used and we need
> to set Cache and Buffer bits.
> 
> In the case of LPAE the cache configuration happens via MAIR0 lookup.
> 
> Signed-off-by: Keerthy 

Reviewed-by: Tom Rini 

-- 
Tom


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[U-Boot] [PATCH 2/6] omap: Set appropriate cache configuration for LPAE and non-LAPE cases

[Keerthy]

Cache configuration methods is different for LPAE and non-LPAE cases.
Hence the bits and the interpretaion is different for two cases.
In case of non-LPAE mode short descriptor format is used and we need
to set Cache and Buffer bits.

In the case of LPAE the cache configuration happens via MAIR0 lookup.

Signed-off-by: Keerthy 
---
 arch/arm/cpu/armv7/omap-common/omap-cache.c | 25 +++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/arm/cpu/armv7/omap-common/omap-cache.c 
b/arch/arm/cpu/armv7/omap-common/omap-cache.c
index ee89f1f..b37163a 100644
--- a/arch/arm/cpu/armv7/omap-common/omap-cache.c
+++ b/arch/arm/cpu/armv7/omap-common/omap-cache.c
@@ -17,7 +17,28 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-#define ARMV7_DCACHE_WRITEBACK  0xe
+/*
+ * Without LPAE short descriptors are used
+ * Set C - Cache Bit3
+ * Set B - Buffer Bit2
+ * The last 2 bits set to 0b10
+ * Do Not set XN bit4
+ * So value is 0xe
+ *
+ * With LPAE cache configuration happens via MAIR0 register
+ * AttrIndx value is 0x3 for picking byte3 for MAIR0 which has 0xFF.
+ * 0xFF maps to Cache writeback with Read and Write Allocate set
+ * The bits[1:0] should have the value 0b01 for the first level
+ * descriptor.
+ * So the value is 0xd
+ */
+
+#ifdef CONFIG_ARMV7_LPAE
+#define ARMV7_DCACHE_POLICYDCACHE_WRITEALLOC
+#else
+#define ARMV7_DCACHE_POLICYDCACHE_WRITEBACK & ~TTB_SECT_XN_MASK
+#endif
+
 #define ARMV7_DOMAIN_CLIENT1
 #define ARMV7_DOMAIN_MASK  (0x3 << 0)
 
@@ -38,7 +59,7 @@ void dram_bank_mmu_setup(int bank)
 
debug("%s: bank: %d\n", __func__, bank);
for (i = start; i < end; i++)
-   set_section_dcache(i, ARMV7_DCACHE_WRITEBACK);
+   set_section_dcache(i, ARMV7_DCACHE_POLICY);
 }
 
 void arm_init_domains(void)
-- 
1.9.1

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