linux-kernel - Re: [PATCH v5 04/10] acpi/video: Move handler installing logic to driver

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Message-ID: <a7d71bff-8577-09f5-5014-5987da1b7c6b@intel.com>
Date:   Fri, 30 Jun 2023 11:42:31 +0200
From:   "Wilczynski, Michal" <michal.wilczynski@...el.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     <linux-acpi@...r.kernel.org>, <dan.j.williams@...el.com>,
        <vishal.l.verma@...el.com>, <lenb@...nel.org>,
        <dave.jiang@...el.com>, <ira.weiny@...el.com>,
        <rui.zhang@...el.com>, <linux-kernel@...r.kernel.org>,
        <nvdimm@...ts.linux.dev>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v5 04/10] acpi/video: Move handler installing logic to
 driver



On 6/29/2023 5:58 PM, Rafael J. Wysocki wrote:
> On Fri, Jun 16, 2023 at 6:51 PM Michal Wilczynski
> <michal.wilczynski@...el.com> wrote:
>> Currently logic for installing notifications from ACPI devices is
>> implemented using notify callback in struct acpi_driver. Preparations
>> are being made to replace acpi_driver with more generic struct
>> platform_driver, which doesn't contain notify callback. Furthermore
>> as of now handlers are being called indirectly through
>> acpi_notify_device(), which decreases performance.
>>
>> Call acpi_dev_install_notify_handler() at the end of .add() callback.
>> Call acpi_dev_remove_notify_handler() at the beginning of .remove()
>> callback. Change arguments passed to the notify function to match with
>> what's required by acpi_install_notify_handler(). Remove .notify
>> callback initialization in acpi_driver.
>>
>> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>> Signed-off-by: Michal Wilczynski <michal.wilczynski@...el.com>
>> ---
>>  drivers/acpi/acpi_video.c | 26 ++++++++++++++++++++++----
>>  1 file changed, 22 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
>> index 62f4364e4460..60b7013d0009 100644
>> --- a/drivers/acpi/acpi_video.c
>> +++ b/drivers/acpi/acpi_video.c
>> @@ -77,7 +77,7 @@ static DEFINE_MUTEX(video_list_lock);
>>  static LIST_HEAD(video_bus_head);
>>  static int acpi_video_bus_add(struct acpi_device *device);
>>  static void acpi_video_bus_remove(struct acpi_device *device);
>> -static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
>> +static void acpi_video_bus_notify(acpi_handle handle, u32 event, void *data);
>>
>>  /*
>>   * Indices in the _BCL method response: the first two items are special,
>> @@ -104,7 +104,6 @@ static struct acpi_driver acpi_video_bus = {
>>         .ops = {
>>                 .add = acpi_video_bus_add,
>>                 .remove = acpi_video_bus_remove,
>> -               .notify = acpi_video_bus_notify,
>>                 },
>>  };
>>
>> @@ -1527,12 +1526,15 @@ static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
>>                                   acpi_osi_is_win8() ? 0 : 1);
>>  }
>>
>> -static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
>> +static void acpi_video_bus_notify(acpi_handle handle, u32 event, void *data)
>>  {
>> -       struct acpi_video_bus *video = acpi_driver_data(device);
>> +       struct acpi_device *device = data;
>> +       struct acpi_video_bus *video;
>>         struct input_dev *input;
>>         int keycode = 0;
>>
>> +       video = acpi_driver_data(device);
>> +
>>         if (!video || !video->input)
>>                 return;
>>
>> @@ -2053,8 +2055,20 @@ static int acpi_video_bus_add(struct acpi_device *device)
>>
>>         acpi_video_bus_add_notify_handler(video);
>>
>> +       error = acpi_dev_install_notify_handler(device,
>> +                                               ACPI_DEVICE_NOTIFY,
>> +                                               acpi_video_bus_notify);
>> +       if (error)
>> +               goto err_remove_and_unregister_video;
> This label name is a bit too long and the second half of it doesn't
> really add any value IMV.  err_remove would be sufficient.

I've seen different patterns in the code, sometimes the label describe what failed,
sometimes it describe what needs to be cleaned up. I don't really have a strong
preference, just thought it might be useful to the reader. Will change as suggested.

>
>> +
>>         return 0;
>>
>> +err_remove_and_unregister_video:
>> +       mutex_lock(&video_list_lock);
>> +       list_del(&video->entry);
>> +       mutex_unlock(&video_list_lock);
>> +       acpi_video_bus_remove_notify_handler(video);
>> +       acpi_video_bus_unregister_backlight(video);
>>  err_put_video:
>>         acpi_video_bus_put_devices(video);
>>         kfree(video->attached_array);
>> @@ -2075,6 +2089,10 @@ static void acpi_video_bus_remove(struct acpi_device *device)
>>
>>         video = acpi_driver_data(device);
>>
>> +       acpi_dev_remove_notify_handler(device,
>> +                                      ACPI_DEVICE_NOTIFY,
>> +                                      acpi_video_bus_notify);
>> +
>>         mutex_lock(&video_list_lock);
>>         list_del(&video->entry);
>>         mutex_unlock(&video_list_lock);
>> --
>> 2.41.0
>>