[PATCH -pm 1/2] SDRC: check for stuck DLL state machine and kick

[Kevin Hilman <khilman@deeprootsystems.com>]

From: Richard Woodruff <r-woodruff2@ti.com>

I'm thinking DLL state is an exceptional condition which happens based
on some wrong early programming when initially setting DLL up.  Some
kind of race between idle features and lock happens early on.  This
patch recognizes the issue and moves state machine into locked state.

Its my guess the kick case won't be executed that often.  As long as
DLL is not on you can mess with idle state.  When its on to mess with
DDR control you need to be in self-refresh and not making
accesses... like in dvfs code.

Tested-by: Mike Chan <mikechan@google.com>
---
 arch/arm/mach-omap2/sleep34xx.S |   22 ++++++++++++++++++++--
 1 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
index aedcf94..c469bbe 100644
--- a/arch/arm/mach-omap2/sleep34xx.S
+++ b/arch/arm/mach-omap2/sleep34xx.S
@@ -595,20 +595,38 @@ wait_sdrc_ok:
         ldr     r5, [r4]
         bic     r5, r5, #0x40
         str     r5, [r4]
-wait_dll_lock:
-        /* Is dll in lock mode? */
+is_dll_in_lock_mode:
         ldr     r4, sdrc_dlla_ctrl
         ldr     r5, [r4]
         tst     r5, #0x4
         bxne    lr
         /* wait till dll locks */
+wait_dll_lock_timed:
         ldr     r4, sdrc_dlla_status
+        mov     r6, #0x2000
+wait_dll_lock:
+        subs    r6, r6, #0x1
+        beq     kick_dll
         ldr     r5, [r4]
         and     r5, r5, #0x4
         cmp     r5, #0x4
         bne     wait_dll_lock
         bx      lr
 
+        /* Kick DLL state machine if lock not started */
+kick_dll:
+	ldr     r4, sdrc_dlla_ctrl	/* get dlla addr */
+	ldr     r5, [r4]		/* grab value */
+	mov	r6, r5			/* save value */
+	orr	r6, r6, #0x10		/* dllidle on */
+	str	r6, [r4]
+	dsb
+	bic	r6, #0x10		/* dllidle off */
+	str	r6, [r4]
+	dsb
+	str	r6, [r4]		/* restore old value */
+	b wait_dll_lock_timed
+
 cm_idlest1_core:
 	.word	CM_IDLEST1_CORE_V
 sdrc_dlla_status:
-- 
1.6.3.2