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Message-ID: <20170623140248.GO26073@mail.corp.redhat.com>
Date: Fri, 23 Jun 2017 16:02:48 +0200
From: Benjamin Tissoires <benjamin.tissoires@...hat.com>
To: Lv Zheng <lv.zheng@...el.com>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
systemd-devel@...ts.freedesktop.org,
Peter Hutterer <peter.hutterer@...-t.net>
Subject: Re: [RFC PATCH v6 1/5] ACPI: button: Add a workaround to fix an
order issue for old userspace
On Jun 21 2017 or thereabouts, Lv Zheng wrote:
> There are platform variations implementing ACPI lid device in different
> ways:
> 1. Some platforms send "open" events to OS and the events arrive before
> button driver is resumed;
> 2. Some platforms send "open" events to OS, but the events arrive after
> button driver is resumed, ex., Samsung N210+;
> 3. Some platforms never send "open" events to OS, but send "open" events to
> update the cached _LID return value, and the update events arrive before
> button driver is resumed;
> 4. Some platforms never send "open" events to OS, but send "open" events to
> update the cached _LID return value, but the update events arrive after
> button driver is resumed, ex., Surface Pro 3;
> 5. Some platforms never send "open" events, _LID returns value sticks to
> "close", ex., Surface Pro 1.
> Currently, all cases work find with systemd 233, but only case 1 works fine
> with systemd 229.
>
> Case 2,4 can be treated as an order issue:
> If the button driver always evaluates _LID after seeing a LID
> notification, there shouldn't be such a problem.
>
> Note that this order issue cannot be fixed by sorting OS drivers' resume
> code:
> 1. When acpi.ec_freeze_events=Y, the order depends on whether PNP0C0D(LID)
> or PNP0C09(EC) appears first in the namespace (probe order).
> 2. Even when acpi.ec_freeze_events=N, which forces OS to handle EC events
> as early as possible, the order issue can still be reproduced due to
> platform delays (reproduce ratio is lower than case 1).
> 3. Some platform simply has a very big delay for LID open events.
>
> This patch tries to fix this issue for systemd 229 by defer sending initial
> lid state 10 seconds later after resume, which ensures EC events can always
> arrive before button driver evaluates _LID. It finally only fixes case 2
> platforms as fixing case 4 platforms needs additional efforts (see known
> issue below).
>
> The users can configure wait timeout via button.lid_notify_timeout.
>
> Known issu:
> 1. systemd/logind 229 still mis-bahaves with case 3,4 platforms
> After seeing a LID "close" event, systemd 229 will wait several seconds
> (HoldoffTimeoutSec) before suspending the platform. Thus on case 4
> platforms, if users close lid, and re-open it during the
> HoldoffTimeoutSec period, there is still no "open" events seen by the
> userspace. Thus systemd still considers the last state as "close" and
> suspends the platform after the HoldoffTimeoutSec times out.
>
> Cc: <systemd-devel@...ts.freedesktop.org>
> Cc: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> Cc: Peter Hutterer <peter.hutterer@...-t.net>
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> ---
NACK on this one (at least in this current form): You are presenting a
device to user space with an unknown state.
If you want to delay the query of the state, you also need to delay the
call of input_register_device().
Cheers,
Benjamin
> drivers/acpi/button.c | 36 ++++++++++++++++++++++++++++++++++--
> 1 file changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index e19f530..67a0d78 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -28,6 +28,7 @@
> #include <linux/proc_fs.h>
> #include <linux/seq_file.h>
> #include <linux/input.h>
> +#include <linux/timer.h>
> #include <linux/slab.h>
> #include <linux/acpi.h>
> #include <acpi/button.h>
> @@ -79,6 +80,7 @@ MODULE_DEVICE_TABLE(acpi, button_device_ids);
> static int acpi_button_add(struct acpi_device *device);
> static int acpi_button_remove(struct acpi_device *device);
> static void acpi_button_notify(struct acpi_device *device, u32 event);
> +static void acpi_lid_timeout(ulong arg);
>
> #ifdef CONFIG_PM_SLEEP
> static int acpi_button_suspend(struct device *dev);
> @@ -104,6 +106,7 @@ static struct acpi_driver acpi_button_driver = {
> struct acpi_button {
> unsigned int type;
> struct input_dev *input;
> + struct timer_list lid_timer;
> char phys[32]; /* for input device */
> unsigned long pushed;
> int last_state;
> @@ -119,6 +122,10 @@ static unsigned long lid_report_interval __read_mostly = 500;
> module_param(lid_report_interval, ulong, 0644);
> MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
>
> +static unsigned long lid_notify_timeout __read_mostly = 10;
> +module_param(lid_notify_timeout, ulong, 0644);
> +MODULE_PARM_DESC(lid_notify_timeout, "Timeout (s) before receiving lid notification");
> +
> /* --------------------------------------------------------------------------
> FS Interface (/proc)
> -------------------------------------------------------------------------- */
> @@ -371,6 +378,15 @@ static int acpi_lid_update_state(struct acpi_device *device)
> return acpi_lid_notify_state(device, state);
> }
>
> +static void acpi_lid_start_timer(struct acpi_device *device,
> + unsigned long msecs)
> +{
> + struct acpi_button *button = acpi_driver_data(device);
> +
> + mod_timer(&button->lid_timer,
> + jiffies + msecs_to_jiffies(msecs));
> +}
> +
> static void acpi_lid_initialize_state(struct acpi_device *device)
> {
> switch (lid_init_state) {
> @@ -386,6 +402,13 @@ static void acpi_lid_initialize_state(struct acpi_device *device)
> }
> }
>
> +static void acpi_lid_timeout(ulong arg)
> +{
> + struct acpi_device *device = (struct acpi_device *)arg;
> +
> + acpi_lid_initialize_state(device);
> +}
> +
> static void acpi_button_notify(struct acpi_device *device, u32 event)
> {
> struct acpi_button *button = acpi_driver_data(device);
> @@ -432,6 +455,8 @@ static int acpi_button_suspend(struct device *dev)
> struct acpi_device *device = to_acpi_device(dev);
> struct acpi_button *button = acpi_driver_data(device);
>
> + if (button->type == ACPI_BUTTON_TYPE_LID)
> + del_timer(&button->lid_timer);
> button->suspended = true;
> return 0;
> }
> @@ -443,7 +468,8 @@ static int acpi_button_resume(struct device *dev)
>
> button->suspended = false;
> if (button->type == ACPI_BUTTON_TYPE_LID)
> - acpi_lid_initialize_state(device);
> + acpi_lid_start_timer(device,
> + lid_notify_timeout * MSEC_PER_SEC);
> return 0;
> }
> #endif
> @@ -490,6 +516,9 @@ static int acpi_button_add(struct acpi_device *device)
> ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
> button->last_state = !!acpi_lid_evaluate_state(device);
> button->last_time = ktime_get();
> + init_timer(&button->lid_timer);
> + setup_timer(&button->lid_timer,
> + acpi_lid_timeout, (ulong)device);
> } else {
> printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
> error = -ENODEV;
> @@ -526,12 +555,13 @@ static int acpi_button_add(struct acpi_device *device)
> if (error)
> goto err_remove_fs;
> if (button->type == ACPI_BUTTON_TYPE_LID) {
> - acpi_lid_initialize_state(device);
> /*
> * This assumes there's only one lid device, or if there are
> * more we only care about the last one...
> */
> lid_device = device;
> + acpi_lid_start_timer(device,
> + lid_notify_timeout * MSEC_PER_SEC);
> }
>
> printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
> @@ -551,6 +581,8 @@ static int acpi_button_remove(struct acpi_device *device)
> struct acpi_button *button = acpi_driver_data(device);
>
> acpi_button_remove_fs(device);
> + if (button->type == ACPI_BUTTON_TYPE_LID)
> + del_timer_sync(&button->lid_timer);
> input_unregister_device(button->input);
> kfree(button);
> return 0;
> --
> 2.7.4
>
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