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[v2,5/5] OMAP3: PM: Clear the SCTLR C bit in asm code to prevent data cache allocation

Message ID 1299740837-27881-6-git-send-email-santosh.shilimkar@ti.com (mailing list archive)
State New, archived
Delegated to: Kevin Hilman
Headers show

Commit Message

Santosh Shilimkar March 10, 2011, 7:07 a.m. UTC
None
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Patch

diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
index d29476e..63f1066 100644
--- a/arch/arm/mach-omap2/sleep34xx.S
+++ b/arch/arm/mach-omap2/sleep34xx.S
@@ -248,6 +248,27 @@  clean_caches:
 	 *  - it executes in a cached space so is faster than refetch per-block
 	 *  - should be faster and will change with kernel
 	 *  - 'might' have to copy address, load and jump to it
+	 * Flush all data from the L1 data cache before disabling
+	 * SCTLR.C bit.
+	 */
+	ldr	r1, kernel_flush
+	mov	lr, pc
+	bx	r1
+
+	/*
+	 * Clear the SCTLR.C bit to prevent further data cache
+	 * allocation. Clearing SCTLR.C would make all the data accesses
+	 * strongly ordered and would not hit the cache.
+	 */
+	mrc	p15, 0, r0, c1, c0, 0
+	bic	r0, r0, #(1 << 2)	@ Disable the C bit
+	mcr	p15, 0, r0, c1, c0, 0
+	isb
+
+	/*
+	 * Invalidate L1 data cache. Even though only invalidate is
+	 * necessary exported flush API is used here. Doing clean
+	 * on already clean cache would be almost NOP.
 	 */
 	ldr	r1, kernel_flush
 	blx	r1
@@ -297,6 +318,12 @@  omap3_do_wfi:
 	nop
 	bl wait_sdrc_ok
 
+	mrc	p15, 0, r0, c1, c0, 0
+	tst	r0, #(1 << 2)		@ Check C bit enabled?
+	orreq	r0, r0, #(1 << 2)	@ Enable the C bit if cleared
+	mcreq	p15, 0, r0, c1, c0, 0
+	isb
+
 /*
  * ===================================
  * == Exit point from non-OFF modes ==