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Date: Wed, 10 Sep 2014 07:43:40 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Maciej Matraszek <m.matraszek@...sung.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH] PM / Domains: add debugfs listing of struct
generic_pm_domain-s
On Wed, Sep 10, 2014 at 01:28:56PM +0200, Maciej Matraszek wrote:
> Add /sys/kernel/debug/pm_genpd/pm_genpd_summary file, which
> lists power domains in the system, their statuses and attached devices,
> resembling /sys/kernel/debug/clk/clk_summary.
>
> Currently it is impossible to inspect (from userland) whether
> a power domain is on or off. And, if it is on, which device blocks it
> from powering down. This change allows developers working on
> embedded devices power efficiency to list all necessary information
> about generic power domains in one place.
>
> The content of pm_genpd/pm_genpd_summary file is generated by iterating
> over all generic power domain in the system, and, for each,
> over registered devices.
>
> Example output:
> $ cat /sys/kernel/debug/pm_genpd/pm_genpd_summary
> domain status slaves
> /device runtime status
> ----------------------------------------------------------------------
> isp-power-domain off
> /devices/soc/12180000.fimc-is suspended
> /devices/soc/12180000.fimc-is/120a0000.fimc-lite suspended
> lcd0-power-domain on
> /devices/soc/11c80000.dsi active
> /devices/soc/11c00000.fimd active
> /devices/soc/11e20000.sysmmu suspended
> g3d-power-domain off
> /devices/soc/13001000.gpu suspended
> mfc-power-domain off
> /devices/soc/13400000.mfc-codec suspended
> /devices/soc/13620000.sysmmu suspended
> cam-power-domain off
> /devices/soc/11830000.jpeg-codec suspended
> /devices/soc/11a60000.sysmmu suspended
> /devices/soc/12180000.fimc-is/120c0000.csis suspended
>
> To enable this feature, compile the kernel with debugfs
> and CONFIG_PM_ADVANCED_DEBUG enabled.
>
> Signed-off-by: Maciej Matraszek <m.matraszek@...sung.com>
> ---
> drivers/base/power/domain.c | 153 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 153 insertions(+)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index eee55c1e5fde..d1aa731ba0db 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2189,3 +2189,156 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
> list_add(&genpd->gpd_list_node, &gpd_list);
> mutex_unlock(&gpd_list_lock);
> }
> +
> +
> +/*** debugfs support ***/
> +
> +#ifdef CONFIG_PM_ADVANCED_DEBUG
> +#include <linux/pm.h>
> +#include <linux/device.h>
> +#include <linux/debugfs.h>
> +#include <linux/kobject.h>
> +static struct dentry *pm_genpd_debugfs_dir;
> +
> +/*
> + * TODO: This function is a slightly modified version of rtpm_status_show
> + * from sysfs.c, but dependencies between PM_GENERIC_DOMAINS and PM_RUNTIME
> + * are too loose to generalize it.
> + */
> +#ifdef CONFIG_PM_RUNTIME
> +static void rtpm_status_str(struct seq_file *s, struct device *dev)
> +{
> + static const char * const status_lookup[] = {
> + [RPM_ACTIVE] = "active",
> + [RPM_RESUMING] = "resuming",
> + [RPM_SUSPENDED] = "suspended",
> + [RPM_SUSPENDING] = "suspending"
> + };
> + const char *p = "";
> +
> + if (dev->power.runtime_error)
> + p = "error";
> + else if (dev->power.disable_depth)
> + p = "unsupported";
> + else if (dev->power.runtime_status < ARRAY_SIZE(status_lookup))
> + p = status_lookup[dev->power.runtime_status];
> + else
> + WARN_ON(1);
> +
> + seq_puts(s, p);
> +}
> +#else
> +static void rtpm_status_str(struct seq_file *s, struct device *dev)
> +{
> + seq_puts(s, "active");
> +}
> +#endif
> +
> +static int pm_genpd_summary_one(struct seq_file *s,
> + struct generic_pm_domain *gpd)
> +{
> + static const char * const status_lookup[] = {
> + [GPD_STATE_ACTIVE] = "on",
> + [GPD_STATE_WAIT_MASTER] = "wait-master",
> + [GPD_STATE_BUSY] = "busy",
> + [GPD_STATE_REPEAT] = "off-in-progress",
> + [GPD_STATE_POWER_OFF] = "off"
> + };
> + struct pm_domain_data *pm_data;
> + const char *kobj_path;
> + struct gpd_link *link;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&gpd->lock);
> + if (ret)
> + return -ERESTARTSYS;
> +
> + if (WARN_ON(gpd->status >= ARRAY_SIZE(status_lookup)))
> + goto exit;
> + seq_printf(s, "%-30s %-15s ", gpd->name, status_lookup[gpd->status]);
> +
> + /*
> + * Modifications on the list require holding locks on both
> + * master and slave, so we are safe.
> + * Also gpd->name is immutable.
> + */
> + list_for_each_entry(link, &gpd->master_links, master_node) {
> + seq_printf(s, "%s", link->slave->name);
> + if (!list_is_last(&link->master_node, &gpd->master_links))
> + seq_puts(s, ", ");
> + }
> +
> + list_for_each_entry(pm_data, &gpd->dev_list, list_node) {
> + kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
> + if (kobj_path == NULL)
> + continue;
> +
> + seq_printf(s, "\n %-50s ", kobj_path);
> + rtpm_status_str(s, pm_data->dev);
> + kfree(kobj_path);
> + }
> +
> + seq_puts(s, "\n");
> +exit:
> + mutex_unlock(&gpd->lock);
> +
> + return 0;
> +}
> +
> +static int pm_genpd_summary_show(struct seq_file *s, void *data)
> +{
> + struct generic_pm_domain *gpd;
> + int ret = 0;
> +
> + seq_puts(s, " domain status slaves\n");
> + seq_puts(s, " /device runtime status\n");
> + seq_puts(s, "----------------------------------------------------------------------\n");
> +
> + ret = mutex_lock_interruptible(&gpd_list_lock);
> + if (ret)
> + return -ERESTARTSYS;
> +
> + list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
> + ret = pm_genpd_summary_one(s, gpd);
> + if (ret)
> + break;
> + }
> + mutex_unlock(&gpd_list_lock);
> +
> + return ret;
> +}
> +
> +static int pm_genpd_summary_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, pm_genpd_summary_show, inode->i_private);
> +}
> +
> +static const struct file_operations pm_genpd_summary_fops = {
> + .open = pm_genpd_summary_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +
> +static int __init pm_genpd_debug_init(void)
> +{
> + struct dentry *d;
> +
> + pm_genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
> +
> + /* No debugfs */
> + if (IS_ERR(pm_genpd_debugfs_dir))
> + return PTR_ERR(pm_genpd_debugfs_dir);
You shouldn't care at all, just do this check:
> + if (!pm_genpd_debugfs_dir)
> + return -ENOMEM;
And all will be fine, because:
> + d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
> + pm_genpd_debugfs_dir, NULL, &pm_genpd_summary_fops);
That call will resolve away to nothing if debugfs is not enabled, and it
doesn't make much sense to do anything with an "error" of no debugfs.
> + if (!d)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +late_initcall(pm_genpd_debug_init);
> +#endif /* CONFIG_PM_ADVANCED_DEBUG */
No tear-down of the debugfs files on shutdown?
thanks,
greg k-h
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