OMAP3: add comments for low power code errata

Errata covered:
- 1.157 & 1.185
- i443
- i581

Tested on N900 and Beagleboard with full RET and OFF modes,
using cpuidle and suspend.
Signed-off-by: NJean Pihet <j-pihet@ti.com>
Acked-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NNishanth Menon <nm@ti.com>
Signed-off-by: NKevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-omap2/pm34xx.c

@@ -146,7 +146,7 @@ static void omap3_core_save_context(void)
 
 	/*
 	 * Force write last pad into memory, as this can fail in some
-	 * cases according to erratas 1.157, 1.185
+	 * cases according to errata 1.157, 1.185
 	 */
 	omap_ctrl_writel(omap_ctrl_readl(OMAP343X_PADCONF_ETK_D14),
 		OMAP343X_CONTROL_MEM_WKUP + 0x2a0);
@@ -433,7 +433,7 @@ void omap_sram_idle(void)
 	/*
 	* On EMU/HS devices ROM code restores a SRDC value
 	* from scratchpad which has automatic self refresh on timeout
-	* of AUTO_CNT = 1 enabled. This takes care of errata 1.142.
+	* of AUTO_CNT = 1 enabled. This takes care of erratum ID i443.
 	* Hence store/restore the SDRC_POWER register here.
 	*/
 	if (omap_rev() >= OMAP3430_REV_ES3_0 &&

arch/arm/mach-omap2/sleep34xx.S

@@ -596,6 +596,7 @@ usettbr0:
  * Internal functions
  */
 
+/* This function implements the erratum ID i443 WA, applies to 34xx >= ES3.0 */
 	.text
 ENTRY(es3_sdrc_fix)
 	ldr	r4, sdrc_syscfg		@ get config addr
@@ -641,6 +642,16 @@ sdrc_manual_1:
 ENTRY(es3_sdrc_fix_sz)
 	.word	. - es3_sdrc_fix
 
+/*
+ * This function implements the erratum ID i581 WA:
+ *  SDRC state restore before accessing the SDRAM
+ *
+ * Only used at return from non-OFF mode. For OFF
+ * mode the ROM code configures the SDRC and
+ * the DPLL before calling the restore code directly
+ * from DDR.
+ */
+
 /* Make sure SDRC accesses are ok */
 wait_sdrc_ok: