[U-Boot] [PATCH v3] arm: am33xx: Initialize EMIF REG_PR_OLD_COUNT for BBB and am335x-evm

[Jyri Sarha]

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 at ti.com>
---
Changes since v2:
- Improved the comment in board/ti/am335x/board.h

Changes since v1:
- Move board specific EMIF_OCP_CONFIG_* definitions to board/ti/am335x/board.h
  and improve the related comment
- Handle also am335x-evms older than revision 1.5

This patch (the first version) has been part of TI's latest 2016LTS
based release and has gone trough our regular tesing as a part of
that. There has been no noticable side effects.

 arch/arm/include/asm/emif.h      |  1 +
 arch/arm/mach-omap2/am33xx/ddr.c |  4 ++++
 board/ti/am335x/board.c          | 15 +++++++++++++++
 board/ti/am335x/board.h          | 13 +++++++++++++
 4 files changed, 33 insertions(+)

diff --git a/arch/arm/include/asm/emif.h b/arch/arm/include/asm/emif.h
index b00dece..9a46340 100644
--- a/arch/arm/include/asm/emif.h
+++ b/arch/arm/include/asm/emif.h
@@ -1171,6 +1171,7 @@ struct emif_regs {
 	u32 sdram_tim1;
 	u32 sdram_tim2;
 	u32 sdram_tim3;
+	u32 ocp_config;
 	u32 read_idle_ctrl;
 	u32 zq_config;
 	u32 temp_alert_config;
diff --git a/arch/arm/mach-omap2/am33xx/ddr.c b/arch/arm/mach-omap2/am33xx/ddr.c
index 6acf30c..690487e 100644
--- a/arch/arm/mach-omap2/am33xx/ddr.c
+++ b/arch/arm/mach-omap2/am33xx/ddr.c
@@ -180,6 +180,10 @@ void config_sdram(const struct emif_regs *regs, int nr)
 	writel(regs->ref_ctrl, &emif_reg[nr]->emif_sdram_ref_ctrl);
 	writel(regs->ref_ctrl, &emif_reg[nr]->emif_sdram_ref_ctrl_shdw);
 	writel(regs->sdram_config, &emif_reg[nr]->emif_sdram_config);
+
+	/* Write REG_COS_COUNT_1, REG_COS_COUNT_2, and REG_PR_OLD_COUNT. */
+	if (regs->ocp_config)
+		writel(regs->ocp_config, &emif_reg[nr]->emif_l3_config);
 }
 
 /**
diff --git a/board/ti/am335x/board.c b/board/ti/am335x/board.c
index da9eab4..b994b42 100644
--- a/board/ti/am335x/board.c
+++ b/board/ti/am335x/board.c
@@ -109,6 +109,16 @@ static const struct emif_regs ddr2_emif_reg_data = {
 	.emif_ddr_phy_ctlr_1 = MT47H128M16RT25E_EMIF_READ_LATENCY,
 };
 
+static const struct emif_regs ddr2_evm_emif_reg_data = {
+	.sdram_config = MT47H128M16RT25E_EMIF_SDCFG,
+	.ref_ctrl = MT47H128M16RT25E_EMIF_SDREF,
+	.sdram_tim1 = MT47H128M16RT25E_EMIF_TIM1,
+	.sdram_tim2 = MT47H128M16RT25E_EMIF_TIM2,
+	.sdram_tim3 = MT47H128M16RT25E_EMIF_TIM3,
+	.ocp_config = EMIF_OCP_CONFIG_AM335X_EVM,
+	.emif_ddr_phy_ctlr_1 = MT47H128M16RT25E_EMIF_READ_LATENCY,
+};
+
 static const struct ddr_data ddr3_data = {
 	.datardsratio0 = MT41J128MJT125_RD_DQS,
 	.datawdsratio0 = MT41J128MJT125_WR_DQS,
@@ -198,6 +208,7 @@ static struct emif_regs ddr3_beagleblack_emif_reg_data = {
 	.sdram_tim1 = MT41K256M16HA125E_EMIF_TIM1,
 	.sdram_tim2 = MT41K256M16HA125E_EMIF_TIM2,
 	.sdram_tim3 = MT41K256M16HA125E_EMIF_TIM3,
+	.ocp_config = EMIF_OCP_CONFIG_BEAGLEBONE_BLACK,
 	.zq_config = MT41K256M16HA125E_ZQ_CFG,
 	.emif_ddr_phy_ctlr_1 = MT41K256M16HA125E_EMIF_READ_LATENCY,
 };
@@ -208,6 +219,7 @@ static struct emif_regs ddr3_evm_emif_reg_data = {
 	.sdram_tim1 = MT41J512M8RH125_EMIF_TIM1,
 	.sdram_tim2 = MT41J512M8RH125_EMIF_TIM2,
 	.sdram_tim3 = MT41J512M8RH125_EMIF_TIM3,
+	.ocp_config = EMIF_OCP_CONFIG_AM335X_EVM,
 	.zq_config = MT41J512M8RH125_ZQ_CFG,
 	.emif_ddr_phy_ctlr_1 = MT41J512M8RH125_EMIF_READ_LATENCY |
 				PHY_EN_DYN_PWRDN,
@@ -486,6 +498,9 @@ void sdram_init(void)
 		config_ddr(400, &ioregs_evmsk, &ddr3_icev2_data,
 			   &ddr3_icev2_cmd_ctrl_data, &ddr3_icev2_emif_reg_data,
 			   0);
+	else if (board_is_gp_evm())
+		config_ddr(266, &ioregs, &ddr2_data,
+			   &ddr2_cmd_ctrl_data, &ddr2_evm_emif_reg_data, 0);
 	else
 		config_ddr(266, &ioregs, &ddr2_data,
 			   &ddr2_cmd_ctrl_data, &ddr2_emif_reg_data, 0);
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");
-- 
1.9.1