[PATCH 6/6] ARM: da850: adjust memory settings for tilcdc

[Bartosz Golaszewski]

Default memory settings of da850 do not meet the throughput/latency
requirements of tilcdc. This results in the image displayed being
incorrect and the following warning being displayed by the LCDC
drm driver:

  tilcdc da8xx_lcdc.0: tilcdc_crtc_irq(0x00000020): FIFO underfow

Reconfigure the LCDC priority to the highest. This is a workaround
for the da850-lcdk board which has the LCD controller enabled in
the device tree, but a long-term, system-wide fix is needed for
all davinci boards.

This patch has been modified for mainline linux. It comes from a
downstream TI release for da850[1].

Original author: Vishwanathrao Badarkhe, Manish <manishv.b at ti.com>

[1] http://arago-project.org/git/projects/linux-davinci.git?p=projects/linux-davinci.git;a=commitdiff;h=b9bd39a34cc02c3ba2fc15539a2f0bc2b68d25da;hp=6f6c795faa6366a4ebc1037a0235edba6018a991

Signed-off-by: Bartosz Golaszewski <bgolaszewski at baylibre.com>
---
 arch/arm/mach-davinci/da8xx-dt.c           | 43 ++++++++++++++++++++++++++++++
 arch/arm/mach-davinci/include/mach/da8xx.h |  4 +++
 2 files changed, 47 insertions(+)

diff --git a/arch/arm/mach-davinci/da8xx-dt.c b/arch/arm/mach-davinci/da8xx-dt.c
index f8ecc02..9d29670 100644
--- a/arch/arm/mach-davinci/da8xx-dt.c
+++ b/arch/arm/mach-davinci/da8xx-dt.c
@@ -44,9 +44,52 @@ static struct of_dev_auxdata da850_auxdata_lookup[] __initdata = {
 
 #ifdef CONFIG_ARCH_DAVINCI_DA850
 
+/*
+ * Adjust the default memory settings to cope with the LCDC
+ *
+ * REVISIT: This issue occurs on other davinci boards as well. Find
+ * a proper system-wide fix.
+ */
+static void da850_lcdc_adjust_memory_bandwidth(void)
+{
+	void __iomem *cfg_mstpri1_base;
+	void __iomem *cfg_mstpri2_base;
+	void __iomem *emifb;
+	u32 val;
+
+	/*
+	 * Default master priorities in reg 0 are all lower by default than LCD
+	 * which is set below to 0. Hence don't need to change here.
+	 */
+
+	/* set EDMA30TC0 and TC1 to lower than LCDC (4 < 0) */
+	cfg_mstpri1_base = DA8XX_SYSCFG0_VIRT(DA8XX_MSTPRI1_REG);
+	val = __raw_readl(cfg_mstpri1_base);
+	val &= 0xFFFF00FF;
+	val |= 4 << 8;             /* 0-high, 7-low priority*/
+	val |= 4 << 12;            /* 0-high, 7-low priority*/
+	__raw_writel(val, cfg_mstpri1_base);
+
+	/*
+	 * Reconfigure the LCDC priority to the highest to ensure that
+	 * the throughput/latency requirements for the LCDC are met.
+	 */
+	cfg_mstpri2_base = DA8XX_SYSCFG0_VIRT(DA8XX_MSTPRI2_REG);
+
+	val = __raw_readl(cfg_mstpri2_base);
+	val &= 0x0fffffff;
+	__raw_writel(val, cfg_mstpri2_base);
+
+	/* set BPRIO */
+	emifb = ioremap(DA8XX_DDR_CTL_BASE, SZ_4K);
+	__raw_writel(0x20, emifb + DA8XX_PBBPR_REG);
+	iounmap(emifb);
+}
+
 static void __init da850_init_machine(void)
 {
 	of_platform_default_populate(NULL, da850_auxdata_lookup, NULL);
+	da850_lcdc_adjust_memory_bandwidth();
 }
 
 static const char *const da850_boards_compat[] __initconst = {
diff --git a/arch/arm/mach-davinci/include/mach/da8xx.h b/arch/arm/mach-davinci/include/mach/da8xx.h
index f9f9713..5549eff 100644
--- a/arch/arm/mach-davinci/include/mach/da8xx.h
+++ b/arch/arm/mach-davinci/include/mach/da8xx.h
@@ -56,6 +56,8 @@ extern unsigned int da850_max_speed;
 #define DA8XX_SYSCFG0_VIRT(x)	(da8xx_syscfg0_base + (x))
 #define DA8XX_JTAG_ID_REG	0x18
 #define DA8XX_HOST1CFG_REG	0x44
+#define DA8XX_MSTPRI1_REG	0x114
+#define DA8XX_MSTPRI2_REG	0x118
 #define DA8XX_CHIPSIG_REG	0x174
 #define DA8XX_CFGCHIP0_REG	0x17c
 #define DA8XX_CFGCHIP1_REG	0x180
@@ -79,6 +81,8 @@ extern unsigned int da850_max_speed;
 #define DA8XX_AEMIF_CTL_BASE	0x68000000
 #define DA8XX_SHARED_RAM_BASE	0x80000000
 #define DA8XX_ARM_RAM_BASE	0xffff0000
+#define DA8XX_DDR_CTL_BASE	0xB0000000
+#define DA8XX_PBBPR_REG		0x00000020
 
 void da830_init(void);
 void da850_init(void);
-- 
2.7.4