ARM: OMAP2PLUS: DSS: Ensure DSS works correctly if display is enabled in bootloader

Resetting DISPC when a DISPC output is enabled causes the DSS to go into an
inconsistent state. Thus if the bootloader has enabled a display, the hwmod code
cannot reset the DISPC module just like that, but the outputs need to be
disabled first.

Add function dispc_disable_outputs() which disables all active overlay manager
and ensure all frame transfers are completed.

Modify omap_dss_reset() to call this function and clear DSS_CONTROL,
DSS_SDI_CONTROL and DSS_PLL_CONTROL so that DSS is in a clean state when the
DSS2 driver starts.

This resolves the hang issue(caused by a L3 error during boot) seen on the
beagle board C3, which has a factory bootloader that enables display. The issue
is resolved with this patch.

Thanks to Tomi and Sricharan for some additional testing.

Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: R, Sricharan <r.sricharan@ti.com>
Signed-off-by: Archit Taneja <archit@ti.com>
[paul@pwsan.com: restructured code, removed omap_{read,write}l(), removed
 cpu_is_omap*() calls and converted to dev_attr]
Signed-off-by: Paul Walmsley <paul@pwsan.com>

1 files changed, 124 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
index 941b5459707f..dce9905d64bb 100644
--- a/arch/arm/mach-omap2/display.c
+++ b/arch/arm/mach-omap2/display.c
@@ -30,6 +30,32 @@
 #include <plat/common.h>
 
 #include "control.h"
+#include "display.h"
+
+#define DISPC_CONTROL		0x0040
+#define DISPC_CONTROL2		0x0238
+#define DISPC_IRQSTATUS		0x0018
+
+#define DSS_SYSCONFIG		0x10
+#define DSS_SYSSTATUS		0x14
+#define DSS_CONTROL		0x40
+#define DSS_SDI_CONTROL		0x44
+#define DSS_PLL_CONTROL		0x48
+
+#define LCD_EN_MASK		(0x1 << 0)
+#define DIGIT_EN_MASK		(0x1 << 1)
+
+#define FRAMEDONE_IRQ_SHIFT	0
+#define EVSYNC_EVEN_IRQ_SHIFT	2
+#define EVSYNC_ODD_IRQ_SHIFT	3
+#define FRAMEDONE2_IRQ_SHIFT	22
+#define FRAMEDONETV_IRQ_SHIFT	24
+
+/*
+ * FRAMEDONE_IRQ_TIMEOUT: how long (in milliseconds) to wait during DISPC
+ *     reset before deciding that something has gone wrong
+ */
+#define FRAMEDONE_IRQ_TIMEOUT		100
 
 static struct platform_device omap_display_device = {
 	.name          = "omapdss",
@@ -174,6 +200,90 @@ int __init omap_display_init(struct omap_dss_board_info *board_data)
 	return r;
 }
 
+static void dispc_disable_outputs(void)
+{
+	u32 v, irq_mask = 0;
+	bool lcd_en, digit_en, lcd2_en = false;
+	int i;
+	struct omap_dss_dispc_dev_attr *da;
+	struct omap_hwmod *oh;
+
+	oh = omap_hwmod_lookup("dss_dispc");
+	if (!oh) {
+		WARN(1, "display: could not disable outputs during reset - could not find dss_dispc hwmod\n");
+		return;
+	}
+
+	if (!oh->dev_attr) {
+		pr_err("display: could not disable outputs during reset due to missing dev_attr\n");
+		return;
+	}
+
+	da = (struct omap_dss_dispc_dev_attr *)oh->dev_attr;
+
+	/* store value of LCDENABLE and DIGITENABLE bits */
+	v = omap_hwmod_read(oh, DISPC_CONTROL);
+	lcd_en = v & LCD_EN_MASK;
+	digit_en = v & DIGIT_EN_MASK;
+
+	/* store value of LCDENABLE for LCD2 */
+	if (da->manager_count > 2) {
+		v = omap_hwmod_read(oh, DISPC_CONTROL2);
+		lcd2_en = v & LCD_EN_MASK;
+	}
+
+	if (!(lcd_en | digit_en | lcd2_en))
+		return; /* no managers currently enabled */
+
+	/*
+	 * If any manager was enabled, we need to disable it before
+	 * DSS clocks are disabled or DISPC module is reset
+	 */
+	if (lcd_en)
+		irq_mask |= 1 << FRAMEDONE_IRQ_SHIFT;
+
+	if (digit_en) {
+		if (da->has_framedonetv_irq) {
+			irq_mask |= 1 << FRAMEDONETV_IRQ_SHIFT;
+		} else {
+			irq_mask |= 1 << EVSYNC_EVEN_IRQ_SHIFT |
+				1 << EVSYNC_ODD_IRQ_SHIFT;
+		}
+	}
+
+	if (lcd2_en)
+		irq_mask |= 1 << FRAMEDONE2_IRQ_SHIFT;
+
+	/*
+	 * clear any previous FRAMEDONE, FRAMEDONETV,
+	 * EVSYNC_EVEN/ODD or FRAMEDONE2 interrupts
+	 */
+	omap_hwmod_write(irq_mask, oh, DISPC_IRQSTATUS);
+
+	/* disable LCD and TV managers */
+	v = omap_hwmod_read(oh, DISPC_CONTROL);
+	v &= ~(LCD_EN_MASK | DIGIT_EN_MASK);
+	omap_hwmod_write(v, oh, DISPC_CONTROL);
+
+	/* disable LCD2 manager */
+	if (da->manager_count > 2) {
+		v = omap_hwmod_read(oh, DISPC_CONTROL2);
+		v &= ~LCD_EN_MASK;
+		omap_hwmod_write(v, oh, DISPC_CONTROL2);
+	}
+
+	i = 0;
+	while ((omap_hwmod_read(oh, DISPC_IRQSTATUS) & irq_mask) !=
+	       irq_mask) {
+		i++;
+		if (i > FRAMEDONE_IRQ_TIMEOUT) {
+			pr_err("didn't get FRAMEDONE1/2 or TV interrupt\n");
+			break;
+		}
+		mdelay(1);
+	}
+}
+
 #define MAX_MODULE_SOFTRESET_WAIT	10000
 int omap_dss_reset(struct omap_hwmod *oh)
 {
@@ -190,6 +300,20 @@ int omap_dss_reset(struct omap_hwmod *oh)
 		if (oc->_clk)
 			clk_enable(oc->_clk);
 
+	dispc_disable_outputs();
+
+	/* clear SDI registers */
+	if (cpu_is_omap3430()) {
+		omap_hwmod_write(0x0, oh, DSS_SDI_CONTROL);
+		omap_hwmod_write(0x0, oh, DSS_PLL_CONTROL);
+	}
+
+	/*
+	 * clear DSS_CONTROL register to switch DSS clock sources to
+	 * PRCM clock, if any
+	 */
+	omap_hwmod_write(0x0, oh, DSS_CONTROL);
+
 	omap_test_timeout((omap_hwmod_read(oh, oh->class->sysc->syss_offs)
 				& SYSS_RESETDONE_MASK),
 			MAX_MODULE_SOFTRESET_WAIT, c);