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>

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);

arch/arm/mach-omap2/display.h

@@ -0,0 +1,29 @@
+/*
+ * display.h - OMAP2+ integration-specific DSS header
+ *
+ * Copyright (C) 2011 Texas Instruments, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ARCH_ARM_MACH_OMAP2_DISPLAY_H
+#define __ARCH_ARM_MACH_OMAP2_DISPLAY_H
+
+#include <linux/kernel.h>
+
+struct omap_dss_dispc_dev_attr {
+	u8	manager_count;
+	bool	has_framedonetv_irq;
+};
+
+#endif

arch/arm/mach-omap2/omap_hwmod_2420_data.c

@@ -943,6 +943,7 @@ static struct omap_hwmod omap2420_dss_dispc_hwmod = {
 	.slaves		= omap2420_dss_dispc_slaves,
 	.slaves_cnt	= ARRAY_SIZE(omap2420_dss_dispc_slaves),
 	.flags		= HWMOD_NO_IDLEST,
+	.dev_attr	= &omap2_3_dss_dispc_dev_attr
 };
 
 /* l4_core -> dss_rfbi */

arch/arm/mach-omap2/omap_hwmod_2430_data.c

@@ -1004,6 +1004,7 @@ static struct omap_hwmod omap2430_dss_dispc_hwmod = {
 	.slaves		= omap2430_dss_dispc_slaves,
 	.slaves_cnt	= ARRAY_SIZE(omap2430_dss_dispc_slaves),
 	.flags		= HWMOD_NO_IDLEST,
+	.dev_attr	= &omap2_3_dss_dispc_dev_attr
 };
 
 /* l4_core -> dss_rfbi */

arch/arm/mach-omap2/omap_hwmod_3xxx_data.c

@@ -1462,6 +1462,7 @@ static struct omap_hwmod omap3xxx_dss_dispc_hwmod = {
 	.slaves		= omap3xxx_dss_dispc_slaves,
 	.slaves_cnt	= ARRAY_SIZE(omap3xxx_dss_dispc_slaves),
 	.flags		= HWMOD_NO_IDLEST,
+	.dev_attr	= &omap2_3_dss_dispc_dev_attr
 };
 
 /*

arch/arm/mach-omap2/omap_hwmod_44xx_data.c

@@ -1327,6 +1327,11 @@ static struct omap_hwmod_addr_space omap44xx_dss_dispc_addrs[] = {
 	{ }
 };
 
+static struct omap_dss_dispc_dev_attr omap44xx_dss_dispc_dev_attr = {
+	.manager_count		= 3,
+	.has_framedonetv_irq	= 1
+};
+
 /* l4_per -> dss_dispc */
 static struct omap_hwmod_ocp_if omap44xx_l4_per__dss_dispc = {
 	.master		= &omap44xx_l4_per_hwmod,
@@ -1357,6 +1362,7 @@ static struct omap_hwmod omap44xx_dss_dispc_hwmod = {
 	},
 	.slaves		= omap44xx_dss_dispc_slaves,
 	.slaves_cnt	= ARRAY_SIZE(omap44xx_dss_dispc_slaves),
+	.dev_attr	= &omap44xx_dss_dispc_dev_attr
 };
 
 /*

arch/arm/mach-omap2/omap_hwmod_common_data.c

@@ -49,3 +49,7 @@ struct omap_hwmod_sysc_fields omap_hwmod_sysc_type2 = {
 	.srst_shift	= SYSC_TYPE2_SOFTRESET_SHIFT,
 };
 
+struct omap_dss_dispc_dev_attr omap2_3_dss_dispc_dev_attr = {
+	.manager_count		= 2,
+	.has_framedonetv_irq	= 0
+};

arch/arm/mach-omap2/omap_hwmod_common_data.h

@@ -16,6 +16,8 @@
 
 #include <plat/omap_hwmod.h>
 
+#include "display.h"
+
 /* Common address space across OMAP2xxx */
 extern struct omap_hwmod_addr_space omap2xxx_uart1_addr_space[];
 extern struct omap_hwmod_addr_space omap2xxx_uart2_addr_space[];
@@ -111,4 +113,6 @@ extern struct omap_hwmod_class omap2xxx_dma_hwmod_class;
 extern struct omap_hwmod_class omap2xxx_mailbox_hwmod_class;
 extern struct omap_hwmod_class omap2xxx_mcspi_class;
 
+extern struct omap_dss_dispc_dev_attr omap2_3_dss_dispc_dev_attr;
+
 #endif