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Date: Thu, 25 Aug 2022 19:55:15 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Vimal Kumar <vimal.kumar32@...il.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
chinmoyghosh2001@...il.com, Mintu Patel <mintupatel89@...il.com>,
Vishal Badole <badolevishal1116@...il.com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2] PM: runtime: Add support to disable wakeup sources
On Thu, Aug 25, 2022 at 7:35 PM Vimal Kumar <vimal.kumar32@...il.com> wrote:
>
> User could find many wakeup sources available in the bsp, which
> they won't be using. Currently users can only get the status and
> list of enabled wakeup sources, but users can't disable it runtime.
What about using the wakeup attribute for devices in sysfs? That
effectively disables/enables a wakeup source.
> It's very difficult to find the driver for each wakeup sources from
> where it's getting enabled and make the changes for disabling it.
Why do you need to enable/disable them individually, though?
> This will help users to disable any wakeup sources at runtime,
> avoiding any code change and re-compilation. A new class attribute
> "disable_ws" will be added in the wakeup calss. If user want to disable
> any wakeup sources, user need to find the wakeup dev node associated
> with the particular wakeup source and write the devnode name to the
> class attribute "disable_ws".
>
> Example:
> Need to disable the wakeup source '1c08000.qcom,pcie'. The dev node
> associated with this wakeup source is:
> cat /sys/class/wakeup3/name ==> "1c08000.qcom,pcie", then for disabling
> this wakeup source :
> echo wakeup3 > /sys/class/wakeup/disable_ws
Wouldn't it be more straightforward to add a "disable" attribute for
wakeup sources?
> Co-developed-by: Mintu Patel <mintupatel89@...il.com>
> Signed-off-by: Mintu Patel <mintupatel89@...il.com>
> Co-developed-by: Vishal Badole <badolevishal1116@...il.com>
> Signed-off-by: Vishal Badole <badolevishal1116@...il.com>
> Signed-off-by: Vimal Kumar <vimal.kumar32@...il.com>
> ---
> Documentation/ABI/testing/sysfs-class-wakeup | 16 +++++
> drivers/base/power/wakeup_stats.c | 65 +++++++++++++++++++-
> 2 files changed, 80 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-wakeup b/Documentation/ABI/testing/sysfs-class-wakeup
> index 754aab8b6dcd..75b9a6fe737a 100644
> --- a/Documentation/ABI/testing/sysfs-class-wakeup
> +++ b/Documentation/ABI/testing/sysfs-class-wakeup
> @@ -74,3 +74,19 @@ Contact: Tri Vo <trong@...roid.com>
> Description:
> The file contains the total amount of time this wakeup source
> has been preventing autosleep, in milliseconds.
> +
> +What: /sys/class/wakeup/disable_ws
> +Date: Aug 2022
> +Contact: Vimal Kumar <vimal.kumar@...il.com>
> +Description:
> + This file can be used to disable a wakeup source at runtime.
> + If user want to disable any wakeup sources, user need to find
> + the wakeup dev node associated with the particular wakeup source
> + and write the devnode name to this file "disable_ws".
> +
> + Example:
> + If user Need to disable the wakeup source '1c08000.qcom,pcie', and
> + the wakeup dev node associated with this wakeup source is:
> + cat /sys/class/wakeup3/name ==> "1c08000.qcom,pcie"
> + Then for disabling this wakeup source :
> + echo wakeup3 > /sys/class/wakeup/disable_ws
> diff --git a/drivers/base/power/wakeup_stats.c b/drivers/base/power/wakeup_stats.c
> index 924fac493c4f..497402a28028 100644
> --- a/drivers/base/power/wakeup_stats.c
> +++ b/drivers/base/power/wakeup_stats.c
> @@ -15,6 +15,7 @@
> #include <linux/kobject.h>
> #include <linux/slab.h>
> #include <linux/timekeeping.h>
> +#include <linux/uaccess.h>
>
> #include "power.h"
>
> @@ -208,9 +209,71 @@ void wakeup_source_sysfs_remove(struct wakeup_source *ws)
> device_unregister(ws->dev);
> }
>
> +static ssize_t disable_ws_store(struct class *class,
> + struct class_attribute *attr,
> + const char *buf, size_t len)
> +{
> + struct device *dev;
> + struct wakeup_source *ws;
> + char *ws_name;
> + int status;
> +
> + ws_name = kzalloc(len+1, GFP_KERNEL);
> + if (!ws_name)
> + return -ENOMEM;
> +
> + if (sscanf(buf, "%s", ws_name) != 1)
> + return -EFAULT;
> +
> + dev = class_find_device_by_name(wakeup_class, ws_name);
> + if (!dev) {
> + pr_err("%s : wakeup device not found\n", __func__);
> + return -EINVAL;
> + }
> +
> + ws = dev_get_drvdata(dev);
> + if (ws->dev->parent != NULL) {
> +
> + status = device_wakeup_disable(ws->dev->parent);
> + if (status < 0) {
> + /* In case of virtual device, return code will be -EINVAL
> + * then unregister the wakeup source associated with it
> + */
> + wakeup_source_unregister(ws);
> + }
> + } else
> + /* If the parent device is NULL, just unregister the wakeup source */
> + wakeup_source_unregister(ws);
> +
> + return len;
> +}
> +
> +static CLASS_ATTR_WO(disable_ws);
> +
> +static struct attribute *wakeup_class_attrs[] = {
> + &class_attr_disable_ws.attr,
> + NULL,
> +};
> +ATTRIBUTE_GROUPS(wakeup_class);
> +
> static int __init wakeup_sources_sysfs_init(void)
> {
> - wakeup_class = class_create(THIS_MODULE, "wakeup");
> + int status;
> +
> + wakeup_class = kzalloc(sizeof(*wakeup_class), GFP_KERNEL);
> + if (!wakeup_class)
> + return -ENOMEM;
> +
> + wakeup_class->name = "wakeup";
> + wakeup_class->owner = THIS_MODULE;
> + wakeup_class->class_groups = wakeup_class_groups;
> +
> + status = class_register(wakeup_class);
> +
> + if (status < 0) {
> + pr_err("%s: class register failed %d\n", __func__, status);
> + return status;
> + }
>
> return PTR_ERR_OR_ZERO(wakeup_class);
> }
> --
> 2.25.1
>
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