Patchwork [2/2] cpufreq: armada-37xx: fix frequency calculation for opp

login
register
mail settings
Submitter Gregory CLEMENT
Date March 8, 2019, 4:47 p.m.
Message ID <20190308164710.10597-3-gregory.clement@bootlin.com>
Download mbox | patch
Permalink /patch/744653/
State New
Headers show

Comments

Gregory CLEMENT - March 8, 2019, 4:47 p.m.
The frequency calculation was based on the current(max) frequency of the
CPU. However for low frequency, the value used was already the parent
frequency divided by a factor of 2.

Instead of using this frequency, this fix directly get the frequency from
the parent clock.

Fixes: 92ce45fb875d ("cpufreq: Add DVFS support for Armada 37xx")
Cc: <stable@vger.kernel.org>
Reported-by: Christian Neubert <christian.neubert.86@gmail.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
---
 drivers/cpufreq/armada-37xx-cpufreq.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)
Viresh Kumar - March 11, 2019, 5:33 a.m.
On 08-03-19, 17:47, Gregory CLEMENT wrote:
> The frequency calculation was based on the current(max) frequency of the
> CPU. However for low frequency, the value used was already the parent
> frequency divided by a factor of 2.
> 
> Instead of using this frequency, this fix directly get the frequency from
> the parent clock.
> 
> Fixes: 92ce45fb875d ("cpufreq: Add DVFS support for Armada 37xx")
> Cc: <stable@vger.kernel.org>
> Reported-by: Christian Neubert <christian.neubert.86@gmail.com>
> Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
> ---
>  drivers/cpufreq/armada-37xx-cpufreq.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
> index ad4463e4266e..a0962463805e 100644
> --- a/drivers/cpufreq/armada-37xx-cpufreq.c
> +++ b/drivers/cpufreq/armada-37xx-cpufreq.c
> @@ -373,11 +373,11 @@ static int __init armada37xx_cpufreq_driver_init(void)
>  	struct armada_37xx_dvfs *dvfs;
>  	struct platform_device *pdev;
>  	unsigned long freq;
> -	unsigned int cur_frequency;
> +	unsigned int cur_frequency, base_frequency;
>  	struct regmap *nb_pm_base, *avs_base;
>  	struct device *cpu_dev;
>  	int load_lvl, ret;
> -	struct clk *clk;
> +	struct clk *clk, *parent;
>  
>  	nb_pm_base =
>  		syscon_regmap_lookup_by_compatible("marvell,armada-3700-nb-pm");
> @@ -413,6 +413,22 @@ static int __init armada37xx_cpufreq_driver_init(void)
>  		return PTR_ERR(clk);
>  	}
>  
> +	parent = clk_get_parent(clk);
> +	if (IS_ERR(parent)) {
> +		dev_err(cpu_dev, "Cannot get parent clock for CPU0\n");
> +		clk_put(clk);
> +		return PTR_ERR(parent);
> +	}
> +
> +	/* Get parent CPU frequency */
> +	base_frequency =  clk_get_rate(parent);
> +
> +	if (!base_frequency) {
> +		dev_err(cpu_dev, "Failed to get parent clock rate for CPU\n");
> +		clk_put(clk);
> +		return -EINVAL;
> +	}
> +
>  	/* Get nominal (current) CPU frequency */
>  	cur_frequency = clk_get_rate(clk);
>  	if (!cur_frequency) {
> @@ -445,7 +461,7 @@ static int __init armada37xx_cpufreq_driver_init(void)
>  	for (load_lvl = ARMADA_37XX_DVFS_LOAD_0; load_lvl < LOAD_LEVEL_NR;
>  	     load_lvl++) {
>  		unsigned long u_volt = avs_map[dvfs->avs[load_lvl]] * 1000;
> -		freq = cur_frequency / dvfs->divider[load_lvl];
> +		freq = base_frequency / dvfs->divider[load_lvl];
>  		ret = dev_pm_opp_add(cpu_dev, freq, u_volt);
>  		if (ret)
>  			goto remove_opp;

Great. I was wondering on why the top frequency was skipped :)

Patch

diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
index ad4463e4266e..a0962463805e 100644
--- a/drivers/cpufreq/armada-37xx-cpufreq.c
+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
@@ -373,11 +373,11 @@  static int __init armada37xx_cpufreq_driver_init(void)
 	struct armada_37xx_dvfs *dvfs;
 	struct platform_device *pdev;
 	unsigned long freq;
-	unsigned int cur_frequency;
+	unsigned int cur_frequency, base_frequency;
 	struct regmap *nb_pm_base, *avs_base;
 	struct device *cpu_dev;
 	int load_lvl, ret;
-	struct clk *clk;
+	struct clk *clk, *parent;
 
 	nb_pm_base =
 		syscon_regmap_lookup_by_compatible("marvell,armada-3700-nb-pm");
@@ -413,6 +413,22 @@  static int __init armada37xx_cpufreq_driver_init(void)
 		return PTR_ERR(clk);
 	}
 
+	parent = clk_get_parent(clk);
+	if (IS_ERR(parent)) {
+		dev_err(cpu_dev, "Cannot get parent clock for CPU0\n");
+		clk_put(clk);
+		return PTR_ERR(parent);
+	}
+
+	/* Get parent CPU frequency */
+	base_frequency =  clk_get_rate(parent);
+
+	if (!base_frequency) {
+		dev_err(cpu_dev, "Failed to get parent clock rate for CPU\n");
+		clk_put(clk);
+		return -EINVAL;
+	}
+
 	/* Get nominal (current) CPU frequency */
 	cur_frequency = clk_get_rate(clk);
 	if (!cur_frequency) {
@@ -445,7 +461,7 @@  static int __init armada37xx_cpufreq_driver_init(void)
 	for (load_lvl = ARMADA_37XX_DVFS_LOAD_0; load_lvl < LOAD_LEVEL_NR;
 	     load_lvl++) {
 		unsigned long u_volt = avs_map[dvfs->avs[load_lvl]] * 1000;
-		freq = cur_frequency / dvfs->divider[load_lvl];
+		freq = base_frequency / dvfs->divider[load_lvl];
 		ret = dev_pm_opp_add(cpu_dev, freq, u_volt);
 		if (ret)
 			goto remove_opp;