patch for SDRAM remap bug

From d8a687de95b57962e85913b41086f2f24a2ef6ea Mon Sep 17 00:00:00 2001
From: Steve Schefter <[email protected]>
Date: Wed, 27 Jun 2012 09:23:04 -0400
Subject: Avoid SDRAM access crash
When remapping the SDRAM with the MMU enabled, we need to ensure that the translation tables are not still in cache before invalidating the TLB. Failure to do so will result in the following crash approximately 50% of the time:

booting kernel from /dev/nand0.kernel.bb
Image Name: Linux-3.3.0PD12.0.0
OS: Linux
Architecture: ARM

   Type:         Kernel Image
   Compression:  uncompressed
   Data Size:    3384824 Bytes =  3.2 MB
   Load Address: 80008000
   Entry Point:  80008000
unable to handle paging request at address 0x80028000
pc : [<8f01f280>]    lr : [<8f005330>]

sp : 8cfff9b0 ip : 0000003f fp : 00000000
r10: 00001000 r9 : 00000000 r8 : 8d2a8f70
r7 : 8f043818 r6 : 0033a5f8 r5 : 8f04381c r4 : 00001000
r3 : 80028000 r2 : 00000fff r1 : 8d2a8f71 r0 : 80028000
Flags: nzCv IRQs off FIQs off Mode SVC_32
[<8f01f280>] (memcpy+0x18/0x20) from [<8f005330>] (uimage_sdram_flush+0x90/0xb8) [<8f005330>] (uimage_sdram_flush+0x90/0xb8) from [<8f0053a4>] (uncompress_copy+0x4c/0x74)

---
 arch/arm/cpu/mmu.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

index c19f931..4ff0430 100644
@@ -165,6 +165,12 @@ static int arm_mmu_remap_sdram(struct memory_bank *bank)
 		pte += 256;
 	}
 
+	asm volatile (
+		"bl __mmu_cache_flush;"
+		:
+		:
+		: "r0", "r1", "r2", "r3", "r6", "r10", "r12", "lr", "cc", "memory"
+	);
 	tlb_invalidate();
 
 	return 0;

1.7.4.1

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  Antony Pavlov

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