arm: am33xx: Initialize EMIF REG_PR_OLD_COUNT for BBB and am335x-evm
Initialize EMIF OCP_CONFIG registers REG_COS_COUNT_1, REG_COS_COUNT_2,
and REG_PR_OLD_COUNT field for Beaglebone-Black and am335x-evm. With
the default values LCDC suffers from DMA FIFO underflows and frame
synchronization lost errors. The initialization values are the highest
that work flawlessly when heavy memory load is generated by CPU. 32bpp
colors were used in the test. On BBB the video mode used 110MHz pixel
clock. The mode supported by the panel of am335x-evm uses 30MHz pixel
clock.
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/board/ti/am335x/board.h b/board/ti/am335x/board.h
index 9776df7..48c139a 100644
--- a/board/ti/am335x/board.h
+++ b/board/ti/am335x/board.h
@@ -11,6 +11,19 @@
#ifndef _BOARD_H_
#define _BOARD_H_
+/**
+ * AM335X (EMIF_4D) EMIF REG_COS_COUNT_1, REG_COS_COUNT_2, and
+ * REG_PR_OLD_COUNT values to avoid LCDC DMA FIFO underflows and Frame
+ * Synchronization Lost errors. The values are the biggest that work
+ * reliably with offered video modes and the memory subsystem on the
+ * boards. These register have are briefly documented in "7.3.3.5.2
+ * Command Starvation" section of AM335x TRM. The REG_COS_COUNT_1 and
+ * REG_COS_COUNT_2 do not have any effect on current versions of
+ * AM335x.
+ */
+#define EMIF_OCP_CONFIG_BEAGLEBONE_BLACK 0x00141414
+#define EMIF_OCP_CONFIG_AM335X_EVM 0x003d3d3d
+
static inline int board_is_bone(void)
{
return board_ti_is("A335BONE");