glamo_fb: Implement screen blanking

This patch implements fb_blank() for the glamo-fb driver, which switches off
the pixel clock (DCLK) for power saving.

We currently delay the actual pixel clock switch until we enter
FB_BLANK_POWERDOWN, since the backlight fade is slow and we don't want the
user to see artefacts on the screen while the backlight is fading out.

So since the X server first sends FB_BLANK_{V,H}SYNC_SUSPEND, we start the
backlight fade here, and only once we get FB_BLANK_POWERDOWN the pixel clock is
disabled.

There are no measurements yet, but the power savings should be double, since
there is no longer any  generation of the high-frequency LCM signals, and
there are no video-related SDRAM accesses anymore.

Signed-off-by: Harald Welte <laforge@openmoko.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/mfd/glamo/glamo-core.h b/drivers/mfd/glamo/glamo-core.h
index ce8d4c7e79e..4c52bc44eaf 100644
--- a/drivers/mfd/glamo/glamo-core.h
+++ b/drivers/mfd/glamo/glamo-core.h
@@ -96,4 +96,10 @@ void glamo_engine_reset(struct glamo_core *glamo, enum glamo_engine engine);
 int glamo_engine_reclock(struct glamo_core *glamo,
 			 enum glamo_engine engine, int ps);
 
+void glamo_engine_clkreg_set(struct glamo_core *glamo,
+			     enum glamo_engine engine,
+			     u_int16_t mask, u_int16_t val);
+
+u_int16_t glamo_engine_clkreg_get(struct glamo_core *glamo,
+				  enum glamo_engine engine);
 #endif /* __GLAMO_CORE_H */