OMAP: McBSP: Let element DMA mode hit retention also

The device no longer hits retention if element DMA
mode is taken for at least the duration of the
serial console timeout. Force element DMA mode to
shut down through smartidle.
Signed-off-by: NEero Nurkkala <ext-eero.nurkkala@nokia.com>
Acked-by: NEduardo Valentin <eduardo.valentin@nokia.com>
Acked-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

arch/arm/plat-omap/mcbsp.c

@@ -343,6 +343,15 @@ static inline void omap34xx_mcbsp_free(struct omap_mcbsp *mcbsp)
 
 		syscon = OMAP_MCBSP_READ(mcbsp->io_base, SYSCON);
 		syscon &= ~(ENAWAKEUP | SIDLEMODE(0x03) | CLOCKACTIVITY(0x03));
+		/*
+		 * HW bug workaround - If no_idle mode is taken, we need to
+		 * go to smart_idle before going to always_idle, or the
+		 * device will not hit retention anymore.
+		 */
+		syscon |= SIDLEMODE(0x02);
+		OMAP_MCBSP_WRITE(mcbsp->io_base, SYSCON, syscon);
+
+		syscon &= ~(SIDLEMODE(0x03));
 		OMAP_MCBSP_WRITE(mcbsp->io_base, SYSCON, syscon);
 
 		OMAP_MCBSP_WRITE(mcbsp->io_base, WAKEUPEN, 0);