linux-kernel - [PATCH v2 18/21] ARM: tegra: cpufreq: Adjust memory frequency with cpu frequency

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Date:	Sat, 19 Feb 2011 14:26:07 -0800
From:	Colin Cross <ccross@...roid.com>
To:	linux-tegra@...r.kernel.org
Cc:	linux-arm-kernel@...ts.infradead.org, konkers@...roid.com,
	olof@...om.net, Colin Cross <ccross@...roid.com>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 18/21] ARM: tegra: cpufreq: Adjust memory frequency with cpu frequency

Signed-off-by: Colin Cross <ccross@...roid.com>
---
 arch/arm/mach-tegra/cpu-tegra.c |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-tegra/cpu-tegra.c b/arch/arm/mach-tegra/cpu-tegra.c
index f02ba60..0e1016a 100644
--- a/arch/arm/mach-tegra/cpu-tegra.c
+++ b/arch/arm/mach-tegra/cpu-tegra.c
@@ -51,6 +51,7 @@ static struct cpufreq_frequency_table freq_table[] = {
 #define NUM_CPUS	2
 
 static struct clk *cpu_clk;
+static struct clk *emc_clk;
 
 static unsigned long target_cpu_speed[NUM_CPUS];
 static DEFINE_MUTEX(tegra_cpu_lock);
@@ -83,6 +84,17 @@ 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);
 
@@ -173,6 +185,13 @@ 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);
 	clk_enable(cpu_clk);
 
 	cpufreq_frequency_table_cpuinfo(policy, freq_table);
@@ -195,6 +214,8 @@ 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;
 }
-- 
1.7.3.1

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