linux-kernel - [RFC PATCH 4/4] cpufreq: tegra: Register a minimum EMC frequency based on the CPU clock

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Date:	Mon, 16 Jun 2014 15:35:13 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	David Airlie <airlied@...ux.ie>,
	Mike Turquette <mturquette@...aro.org>,
	myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
	devicetree@...r.kernel.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org, dri-devel@...ts.freedesktop.org
Cc:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Subject: [RFC PATCH 4/4] cpufreq: tegra: Register a minimum EMC frequency based on the CPU clock

Instead of setting a direct correlation to the CPU frequency. This allows
for other devices to influence the final effective EMC frequency.

In the future, this should be done instead by an ACTMON driver,
which would also take load stats into account when calculating the
floor EMC frequency.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
---
 drivers/cpufreq/tegra-cpufreq.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c
index 8084c7f..64935f8 100644
--- a/drivers/cpufreq/tegra-cpufreq.c
+++ b/drivers/cpufreq/tegra-cpufreq.c
@@ -26,6 +26,7 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/platform_data/tegra_emc.h>
 
 static struct cpufreq_frequency_table freq_table[] = {
 	{ .frequency = 216000 },
@@ -44,7 +45,6 @@ static struct cpufreq_frequency_table freq_table[] = {
 static struct clk *cpu_clk;
 static struct clk *pll_x_clk;
 static struct clk *pll_p_clk;
-static struct clk *emc_clk;
 static bool pll_x_prepared;
 
 static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
@@ -96,15 +96,15 @@ static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 	int ret = 0;
 
 	/*
-	 * Vote on memory bus frequency based on cpu frequency
+	 * Set minimum 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 */
+		tegra124_emc_set_floor(600000000); /* cpu 816 MHz, emc max */
 	else if (rate >= 456000)
-		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
+		tegra124_emc_set_floor(300000000); /* cpu 456 MHz, emc 150Mhz */
 	else
-		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
+		tegra124_emc_set_floor(100000000);  /* emc 50Mhz */
 
 	/*
 	 * target freq == pll_p, don't need to take extra reference to pll_x_clk
@@ -141,14 +141,12 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 	if (policy->cpu >= NUM_CPUS)
 		return -EINVAL;
 
-	clk_prepare_enable(emc_clk);
 	clk_prepare_enable(cpu_clk);
 
 	/* FIXME: what's the actual transition time? */
 	ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 	if (ret) {
 		clk_disable_unprepare(cpu_clk);
-		clk_disable_unprepare(emc_clk);
 		return ret;
 	}
 
@@ -160,7 +158,6 @@ static int tegra_cpu_init(struct cpufreq_policy *policy)
 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 {
 	clk_disable_unprepare(cpu_clk);
-	clk_disable_unprepare(emc_clk);
 	return 0;
 }
 
@@ -194,19 +191,12 @@ static int __init tegra_cpufreq_init(void)
 	if (IS_ERR(pll_p_clk))
 		return PTR_ERR(pll_p_clk);
 
-	emc_clk = clk_get_sys("cpu", "emc");
-	if (IS_ERR(emc_clk)) {
-		clk_put(cpu_clk);
-		return PTR_ERR(emc_clk);
-	}
-
 	return cpufreq_register_driver(&tegra_cpufreq_driver);
 }
 
 static void __exit tegra_cpufreq_exit(void)
 {
         cpufreq_unregister_driver(&tegra_cpufreq_driver);
-	clk_put(emc_clk);
 	clk_put(cpu_clk);
 }
 
-- 
1.9.3

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