Merge branch 'linux-tegra-2.6.36' into android-tegra-2.6.36

11 files changed, 352 insertions, 4 deletions

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index ef028cd62734..8269eea7ee77 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -75,6 +75,10 @@ config TEGRA_FIQ_DEBUGGER
 
 endif
 
+config TEGRA_EMC_SCALING_ENABLE
+	bool "Enable scaling the memory frequency"
+	default n
+
 config TEGRA_CPU_DVFS
 	bool "Enable voltage scaling on Tegra CPU"
 	default y
diff --git a/arch/arm/mach-tegra/Makefile b/arch/arm/mach-tegra/Makefile
index 6de6bc4c762e..9b8bdf9f5625 100644
--- a/arch/arm/mach-tegra/Makefile
+++ b/arch/arm/mach-tegra/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += tegra2_dvfs.o
 obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += tegra2_fuse.o
 obj-$(CONFIG_ARCH_TEGRA_2x_SOC)         += suspend-t2.o
 obj-$(CONFIG_ARCH_TEGRA_2x_SOC)		+= tegra2_save.o
+obj-$(CONFIG_ARCH_TEGRA_2x_SOC)		+= tegra2_emc.o
 obj-$(CONFIG_CPU_V7)			+= cortex-a9.o
 
 obj-$(CONFIG_ARCH_TEGRA_2x_SOC)		+= pinmux-t2-tables.o
diff --git a/arch/arm/mach-tegra/clock.c b/arch/arm/mach-tegra/clock.c
index 124af0f78782..e3936af38356 100644
--- a/arch/arm/mach-tegra/clock.c
+++ b/arch/arm/mach-tegra/clock.c
@@ -350,6 +350,7 @@ int clk_set_rate(struct clk *c, unsigned long rate)
 	int ret = 0;
 	unsigned long flags;
 	unsigned long old_rate;
+	long new_rate;
 
 	clk_lock_save(c, flags);
 
@@ -363,6 +364,17 @@ int clk_set_rate(struct clk *c, unsigned long rate)
 	if (rate > c->max_rate)
 		rate = c->max_rate;
 
+	if (c->ops && c->ops->round_rate) {
+		new_rate = c->ops->round_rate(c, rate);
+
+		if (new_rate < 0) {
+			ret = new_rate;
+			goto out;
+		}
+
+		rate = new_rate;
+	}
+
 	if (clk_is_auto_dvfs(c) && rate > old_rate && c->refcnt > 0) {
 		ret = tegra_dvfs_set_rate(c, rate);
 		if (ret)
diff --git a/arch/arm/mach-tegra/cpu-tegra.c b/arch/arm/mach-tegra/cpu-tegra.c
index 1be794d015cf..d8c103e8964c 100644
--- a/arch/arm/mach-tegra/cpu-tegra.c
+++ b/arch/arm/mach-tegra/cpu-tegra.c
@@ -59,6 +59,7 @@ static struct cpufreq_frequency_table freq_table[] = {
 #define NUM_CPUS	2
 
 static struct clk *cpu_clk;
+static struct clk *emc_clk;
 
 static struct workqueue_struct *workqueue;
 
@@ -115,6 +116,17 @@ static int tegra_update_cpu_speed(unsigned long rate)
 	if (freqs.old == freqs.new)
 		return ret;
 
+	/*
+	 * Vote on memory bus frequency based on cpu frequency
+	 * This sets the minimum frequency, display or avp may request higher
+	 */
+	if (rate >= 816000)
+		clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
+	else if (rate >= 456000)
+		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
+	else
+		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
+
 	for_each_online_cpu(freqs.cpu)
 		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 
@@ -336,6 +348,13 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 	if (IS_ERR(cpu_clk))
 		return PTR_ERR(cpu_clk);
 
+	emc_clk = clk_get_sys("cpu", "emc");
+	if (IS_ERR(emc_clk)) {
+		clk_put(cpu_clk);
+		return PTR_ERR(emc_clk);
+	}
+	clk_enable(emc_clk);
+
 	cpufreq_frequency_table_cpuinfo(policy, freq_table);
 	cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 	policy->cur = tegra_getspeed(policy->cpu);
@@ -358,6 +377,8 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 {
 	cpufreq_frequency_table_cpuinfo(policy, freq_table);
+	clk_disable(emc_clk);
+	clk_put(emc_clk);
 	clk_put(cpu_clk);
 	return 0;
 }
diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c
index d3bd446289dd..eef598e456f1 100644
--- a/arch/arm/mach-tegra/tegra2_clocks.c
+++ b/arch/arm/mach-tegra/tegra2_clocks.c
@@ -32,6 +32,7 @@
 
 #include "clock.h"
 #include "fuse.h"
+#include "tegra2_emc.h"
 
 #define RST_DEVICES			0x004
 #define RST_DEVICES_SET			0x300
@@ -1021,6 +1022,53 @@ static struct clk_ops tegra_periph_clk_ops = {
 	.reset			= &tegra2_periph_clk_reset,
 };
 
+/* External memory controller clock ops */
+static void tegra2_emc_clk_init(struct clk *c)
+{
+	tegra2_periph_clk_init(c);
+	c->max_rate = clk_get_rate_locked(c);
+}
+
+static long tegra2_emc_clk_round_rate(struct clk *c, unsigned long rate)
+{
+	long new_rate = rate;
+
+	new_rate = tegra_emc_round_rate(new_rate);
+	if (new_rate < 0)
+		return c->max_rate;
+
+	BUG_ON(new_rate != tegra2_periph_clk_round_rate(c, new_rate));
+
+	return new_rate;
+}
+
+static int tegra2_emc_clk_set_rate(struct clk *c, unsigned long rate)
+{
+	int ret;
+	/* The Tegra2 memory controller has an interlock with the clock
+	 * block that allows memory shadowed registers to be updated,
+	 * and then transfer them to the main registers at the same
+	 * time as the clock update without glitches. */
+	ret = tegra_emc_set_rate(rate);
+	if (ret < 0)
+		return ret;
+
+	ret = tegra2_periph_clk_set_rate(c, rate);
+	udelay(1);
+
+	return ret;
+}
+
+static struct clk_ops tegra_emc_clk_ops = {
+	.init			= &tegra2_emc_clk_init,
+	.enable			= &tegra2_periph_clk_enable,
+	.disable		= &tegra2_periph_clk_disable,
+	.set_parent		= &tegra2_periph_clk_set_parent,
+	.set_rate		= &tegra2_emc_clk_set_rate,
+	.round_rate		= &tegra2_emc_clk_round_rate,
+	.reset			= &tegra2_periph_clk_reset,
+};
+
 /* Clock doubler ops */
 static void tegra2_clk_double_init(struct clk *c)
 {
@@ -1157,7 +1205,8 @@ static void tegra_clk_shared_bus_update(struct clk *bus)
 			rate = max(c->u.shared_bus_user.rate, rate);
 	}
 
-	clk_set_rate(bus, rate);
+	if (rate != clk_get_rate(bus))
+		clk_set_rate(bus, rate);
 };
 
 static void tegra_clk_shared_bus_init(struct clk *c)
@@ -1839,6 +1888,18 @@ static struct clk_mux_sel mux_clk_32k[] = {
 	{ 0, 0},
 };
 
+static struct clk tegra_clk_emc = {
+	.name = "emc",
+	.ops = &tegra_emc_clk_ops,
+	.reg = 0x19c,
+	.max_rate = 800000000,
+	.inputs = mux_pllm_pllc_pllp_clkm,
+	.flags = MUX | DIV_U71 | PERIPH_EMC_ENB,
+	.u.periph = {
+		.clk_num = 57,
+	},
+};
+
 #define PERIPH_CLK(_name, _dev, _con, _clk_num, _reg, _max, _inputs, _flags) \
 	{						\
 		.name      = _name,			\
@@ -1927,13 +1988,17 @@ struct clk tegra_list_clks[] = {
 	PERIPH_CLK("usbd",	"fsl-tegra-udc",	NULL,	22,	0,	480000000, mux_clk_m,			0), /* requires min voltage */
 	PERIPH_CLK("usb2",	"tegra-ehci.1",		NULL,	58,	0,	480000000, mux_clk_m,			0), /* requires min voltage */
 	PERIPH_CLK("usb3",	"tegra-ehci.2",		NULL,	59,	0,	480000000, mux_clk_m,			0), /* requires min voltage */
-	PERIPH_CLK("emc",	"emc",			NULL,	57,	0x19c,	800000000, mux_pllm_pllc_pllp_clkm,	MUX | DIV_U71 | PERIPH_EMC_ENB),
 	PERIPH_CLK("dsi",	"dsi",			NULL,	48,	0,	500000000, mux_plld,			0), /* scales with voltage */
 	PERIPH_CLK("csi",	"tegra_camera",		"csi",	52,	0,	72000000,  mux_pllp_out3,		0),
 	PERIPH_CLK("isp",	"tegra_camera",		"isp",	23,	0,	150000000, mux_clk_m,			0), /* same frequency as VI */
 	PERIPH_CLK("csus",	"tegra_camera",		"csus",	92,	0,	150000000, mux_clk_m,			PERIPH_NO_RESET),
 
 	SHARED_CLK("avp.sclk",	"tegra-avp",		"sclk",	&tegra_clk_sclk),
+	SHARED_CLK("avp.emc",	"tegra-avp",		"emc",	&tegra_clk_emc),
+	SHARED_CLK("cpu.emc",	"cpu",			"emc",	&tegra_clk_emc),
+	SHARED_CLK("disp1.emc",	"tegradc.0",		"emc",	&tegra_clk_emc),
+	SHARED_CLK("disp2.emc",	"tegradc.1",		"emc",	&tegra_clk_emc),
+	SHARED_CLK("hdmi.emc",	"hdmi",			"emc",	&tegra_clk_emc),
 };
 
 #define CLK_DUPLICATE(_name, _dev, _con)		\
@@ -2008,6 +2073,7 @@ struct clk *tegra_ptr_clks[] = {
 	&tegra_clk_virtual_cpu,
 	&tegra_clk_blink,
 	&tegra_clk_cop,
+	&tegra_clk_emc,
 };
 
 static void tegra2_init_one_clock(struct clk *c)
diff --git a/arch/arm/mach-tegra/tegra2_dvfs.c b/arch/arm/mach-tegra/tegra2_dvfs.c
index 1bc1c4dce0d2..b58a7d2ef92d 100644
--- a/arch/arm/mach-tegra/tegra2_dvfs.c
+++ b/arch/arm/mach-tegra/tegra2_dvfs.c
@@ -150,6 +150,7 @@ static struct dvfs dvfs_init[] = {
 	CPU_DVFS("cpu", 3, MHZ, 730, 760, 845, 845, 1000),
 
 	/* Core voltages (mV):       950,    1000,   1100,   1200,   1275 */
+	CORE_DVFS("emc",     1, KHZ, 57000,  333000, 333000, 666000, 666000),
 
 #if 0
 	/*
diff --git a/arch/arm/mach-tegra/tegra2_emc.c b/arch/arm/mach-tegra/tegra2_emc.c
new file mode 100644
index 000000000000..bd4fa27b2086
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra2_emc.c
@@ -0,0 +1,172 @@
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *	Colin Cross <ccross@google.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+
+#include <mach/iomap.h>
+
+#include "tegra2_emc.h"
+
+#ifdef CONFIG_TEGRA_EMC_SCALING_ENABLE
+static bool emc_enable = true;
+#else
+static bool emc_enable;
+#endif
+module_param(emc_enable, bool, 0644);
+
+static void __iomem *emc = IO_ADDRESS(TEGRA_EMC_BASE);
+static const struct tegra_emc_table *tegra_emc_table;
+static int tegra_emc_table_size;
+
+static inline void emc_writel(u32 val, unsigned long addr)
+{
+	writel(val, emc + addr);
+}
+
+static inline u32 emc_readl(unsigned long addr)
+{
+	return readl(emc + addr);
+}
+
+static const unsigned long emc_reg_addr[TEGRA_EMC_NUM_REGS] = {
+	0x2c,	/* RC */
+	0x30,	/* RFC */
+	0x34,	/* RAS */
+	0x38,	/* RP */
+	0x3c,	/* R2W */
+	0x40,	/* W2R */
+	0x44,	/* R2P */
+	0x48,	/* W2P */
+	0x4c,	/* RD_RCD */
+	0x50,	/* WR_RCD */
+	0x54,	/* RRD */
+	0x58,	/* REXT */
+	0x5c,	/* WDV */
+	0x60,	/* QUSE */
+	0x64,	/* QRST */
+	0x68,	/* QSAFE */
+	0x6c,	/* RDV */
+	0x70,	/* REFRESH */
+	0x74,	/* BURST_REFRESH_NUM */
+	0x78,	/* PDEX2WR */
+	0x7c,	/* PDEX2RD */
+	0x80,	/* PCHG2PDEN */
+	0x84,	/* ACT2PDEN */
+	0x88,	/* AR2PDEN */
+	0x8c,	/* RW2PDEN */
+	0x90,	/* TXSR */
+	0x94,	/* TCKE */
+	0x98,	/* TFAW */
+	0x9c,	/* TRPAB */
+	0xa0,	/* TCLKSTABLE */
+	0xa4,	/* TCLKSTOP */
+	0xa8,	/* TREFBW */
+	0xac,	/* QUSE_EXTRA */
+	0x114,	/* FBIO_CFG6 */
+	0xb0,	/* ODT_WRITE */
+	0xb4,	/* ODT_READ */
+	0x104,	/* FBIO_CFG5 */
+	0x2bc,	/* CFG_DIG_DLL */
+	0x2c0,	/* DLL_XFORM_DQS */
+	0x2c4,	/* DLL_XFORM_QUSE */
+	0x2e0,	/* ZCAL_REF_CNT */
+	0x2e4,	/* ZCAL_WAIT_CNT */
+	0x2a8,	/* AUTO_CAL_INTERVAL */
+	0x2d0,	/* CFG_CLKTRIM_0 */
+	0x2d4,	/* CFG_CLKTRIM_1 */
+	0x2d8,	/* CFG_CLKTRIM_2 */
+};
+
+/* Select the closest EMC rate that is higher than the requested rate */
+long tegra_emc_round_rate(unsigned long rate)
+{
+	int i;
+	int best = -1;
+	unsigned long distance = ULONG_MAX;
+
+	if (!tegra_emc_table)
+		return -EINVAL;
+
+	if (!emc_enable)
+		return -EINVAL;
+
+	pr_debug("%s: %lu\n", __func__, rate);
+
+	/* The EMC clock rate is twice the bus rate, and the bus rate is
+	 * measured in kHz */
+	rate = rate / 2 / 1000;
+
+	for (i = 0; i < tegra_emc_table_size; i++) {
+		if (tegra_emc_table[i].rate >= rate &&
+		    (tegra_emc_table[i].rate - rate) < distance) {
+			distance = tegra_emc_table[i].rate - rate;
+			best = i;
+		}
+	}
+
+	if (best < 0)
+		return -EINVAL;
+
+	pr_debug("%s: using %lu\n", __func__, tegra_emc_table[best].rate);
+
+	return tegra_emc_table[best].rate * 2 * 1000;
+}
+
+/* The EMC registers have shadow registers.  When the EMC clock is updated
+ * in the clock controller, the shadow registers are copied to the active
+ * registers, allowing glitchless memory bus frequency changes.
+ * This function updates the shadow registers for a new clock frequency,
+ * and relies on the clock lock on the emc clock to avoid races between
+ * multiple frequency changes */
+int tegra_emc_set_rate(unsigned long rate)
+{
+	int i;
+	int j;
+
+	if (!tegra_emc_table)
+		return -EINVAL;
+
+	/* The EMC clock rate is twice the bus rate, and the bus rate is
+	 * measured in kHz */
+	rate = rate / 2 / 1000;
+
+	for (i = 0; i < tegra_emc_table_size; i++)
+		if (tegra_emc_table[i].rate == rate)
+			break;
+
+	if (i >= tegra_emc_table_size)
+		return -EINVAL;
+
+	pr_debug("%s: setting to %lu\n", __func__, rate);
+
+	for (j = 0; j < TEGRA_EMC_NUM_REGS; j++)
+		emc_writel(tegra_emc_table[i].regs[j], emc_reg_addr[j]);
+
+	emc_readl(tegra_emc_table[i].regs[TEGRA_EMC_NUM_REGS - 1]);
+
+	return 0;
+}
+
+void tegra_init_emc(const struct tegra_emc_table *table, int table_size)
+{
+	tegra_emc_table = table;
+	tegra_emc_table_size = table_size;
+}
diff --git a/arch/arm/mach-tegra/tegra2_emc.h b/arch/arm/mach-tegra/tegra2_emc.h
new file mode 100644
index 000000000000..3515e57fd0d9
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra2_emc.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *	Colin Cross <ccross@google.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#define TEGRA_EMC_NUM_REGS 46
+
+struct tegra_emc_table {
+	unsigned long rate;
+	u32 regs[TEGRA_EMC_NUM_REGS];
+};
+
+int tegra_emc_set_rate(unsigned long rate);
+long tegra_emc_round_rate(unsigned long rate);
+void tegra_init_emc(const struct tegra_emc_table *table, int table_size);
diff --git a/drivers/media/video/tegra/avp/avp_svc.c b/drivers/media/video/tegra/avp/avp_svc.c
index 57cd8019c305..2eed2891e556 100644
--- a/drivers/media/video/tegra/avp/avp_svc.c
+++ b/drivers/media/video/tegra/avp/avp_svc.c
@@ -82,6 +82,7 @@ struct avp_svc_info {
 	struct avp_clk			clks[NUM_CLK_REQUESTS];
 	/* used for dvfs */
 	struct clk			*sclk;
+	struct clk			*emcclk;
 
 	struct mutex			clk_lock;
 
@@ -352,6 +353,7 @@ static void do_svc_module_clock(struct avp_svc_info *avp_svc,
 	aclk = &avp_svc->clks[mod->clk_req];
 	if (msg->enable) {
 		if (aclk->refcnt++ == 0) {
+			clk_enable(avp_svc->emcclk);
 			clk_enable(avp_svc->sclk);
 			clk_enable(aclk->clk);
 		}
@@ -362,6 +364,7 @@ static void do_svc_module_clock(struct avp_svc_info *avp_svc,
 		} else if (--aclk->refcnt == 0) {
 			clk_disable(aclk->clk);
 			clk_disable(avp_svc->sclk);
+			clk_disable(avp_svc->emcclk);
 		}
 	}
 	mutex_unlock(&avp_svc->clk_lock);
@@ -631,8 +634,9 @@ void avp_svc_stop(struct avp_svc_info *avp_svc)
 			pr_info("%s: remote left clock '%s' on\n", __func__,
 				aclk->mod->name);
 			clk_disable(aclk->clk);
-			/* sclk was enabled once for every clock */
+			/* sclk/emcclk was enabled once for every clock */
 			clk_disable(avp_svc->sclk);
+			clk_disable(avp_svc->emcclk);
 		}
 		aclk->refcnt = 0;
 	}
@@ -682,6 +686,21 @@ struct avp_svc_info *avp_svc_init(struct platform_device *pdev,
 		ret = -ENOENT;
 		goto err_get_clks;
 	}
+
+	avp_svc->emcclk = clk_get(&pdev->dev, "emc");
+	if (IS_ERR(avp_svc->emcclk)) {
+		pr_err("avp_svc: Couldn't get emcclk for dvfs\n");
+		ret = -ENOENT;
+		goto err_get_clks;
+	}
+
+	/*
+	 * The emc is a shared clock, it will be set to the highest
+	 * requested rate from any user.  Set the rate to ULONG_MAX to
+	 * always request the max rate whenever this request is enabled
+	 */
+	clk_set_rate(avp_svc->emcclk, ULONG_MAX);
+
 	avp_svc->rpc_node = rpc_node;
 
 	mutex_init(&avp_svc->clk_lock);
@@ -694,6 +713,8 @@ err_get_clks:
 			clk_put(avp_svc->clks[i].clk);
 	if (!IS_ERR_OR_NULL(avp_svc->sclk))
 		clk_put(avp_svc->sclk);
+	if (!IS_ERR_OR_NULL(avp_svc->emcclk))
+		clk_put(avp_svc->emcclk);
 err_alloc:
 	return ERR_PTR(ret);
 }
@@ -705,6 +726,7 @@ void avp_svc_destroy(struct avp_svc_info *avp_svc)
 	for (i = 0; i < NUM_CLK_REQUESTS; i++)
 		clk_put(avp_svc->clks[i].clk);
 	clk_put(avp_svc->sclk);
+	clk_put(avp_svc->emcclk);
 
 	kfree(avp_svc);
 }
diff --git a/drivers/video/tegra/dc/dc.c b/drivers/video/tegra/dc/dc.c
index 5c65e3c1a61a..3c3a4754b7dc 100644
--- a/drivers/video/tegra/dc/dc.c
+++ b/drivers/video/tegra/dc/dc.c
@@ -967,6 +967,7 @@ static bool _tegra_dc_enable(struct tegra_dc *dc)
 	tegra_dc_setup_clk(dc, dc->clk);
 
 	clk_enable(dc->clk);
+	clk_enable(dc->emc_clk);
 	enable_irq(dc->irq);
 
 	tegra_dc_init(dc);
@@ -997,6 +998,7 @@ static void _tegra_dc_disable(struct tegra_dc *dc)
 	if (dc->out_ops && dc->out_ops->disable)
 		dc->out_ops->disable(dc);
 
+	clk_disable(dc->emc_clk);
 	clk_disable(dc->clk);
 	tegra_dvfs_set_rate(dc->clk, 0);
 
@@ -1029,6 +1031,7 @@ static int tegra_dc_probe(struct nvhost_device *ndev)
 {
 	struct tegra_dc *dc;
 	struct clk *clk;
+	struct clk *emc_clk;
 	struct resource	*res;
 	struct resource *base_res;
 	struct resource *fb_mem = NULL;
@@ -1085,7 +1088,22 @@ static int tegra_dc_probe(struct nvhost_device *ndev)
 		goto err_iounmap_reg;
 	}
 
+	emc_clk = clk_get(&ndev->dev, "emc");
+	if (IS_ERR_OR_NULL(emc_clk)) {
+		dev_err(&ndev->dev, "can't get emc clock\n");
+		ret = -ENOENT;
+		goto err_put_clk;
+	}
+
+	/*
+	 * The emc is a shared clock, it will be set to the highest
+	 * requested rate from any user.  Set the rate to ULONG_MAX to
+	 * always request the max rate whenever this request is enabled
+	 */
+	clk_set_rate(emc_clk, ULONG_MAX);
+
 	dc->clk = clk;
+	dc->emc_clk = emc_clk;
 	dc->base_res = base_res;
 	dc->base = base;
 	dc->irq = irq;
@@ -1108,7 +1126,7 @@ static int tegra_dc_probe(struct nvhost_device *ndev)
 			dev_name(&ndev->dev), dc)) {
 		dev_err(&ndev->dev, "request_irq %d failed\n", irq);
 		ret = -EBUSY;
-		goto err_put_clk;
+		goto err_put_emc_clk;
 	}
 
 	/* hack to ballence enable_irq calls in _tegra_dc_enable() */
@@ -1158,6 +1176,8 @@ static int tegra_dc_probe(struct nvhost_device *ndev)
 
 err_free_irq:
 	free_irq(irq, dc);
+err_put_emc_clk:
+	clk_put(emc_clk);
 err_put_clk:
 	clk_put(clk);
 err_iounmap_reg:
@@ -1187,6 +1207,7 @@ static int tegra_dc_remove(struct nvhost_device *ndev)
 		_tegra_dc_disable(dc);
 
 	free_irq(dc->irq, dc);
+	clk_put(dc->emc_clk);
 	clk_put(dc->clk);
 	iounmap(dc->base);
 	if (dc->fb_mem)
diff --git a/drivers/video/tegra/dc/dc_priv.h b/drivers/video/tegra/dc/dc_priv.h
index 7d0e340a6ee2..253d03f057d7 100644
--- a/drivers/video/tegra/dc/dc_priv.h
+++ b/drivers/video/tegra/dc/dc_priv.h
@@ -60,6 +60,7 @@ struct tegra_dc {
 	int				irq;
 
 	struct clk			*clk;
+	struct clk			*emc_clk;
 
 	bool				enabled;