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

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Message-ID: <CAJZ5v0hZ-2Ee0DCcgzHJrOikRTOJuCbEbQj24xui_-vmbd+47Q@mail.gmail.com>
Date:   Thu, 29 Jun 2023 17:58:00 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Michal Wilczynski <michal.wilczynski@...el.com>
Cc:     linux-acpi@...r.kernel.org, rafael@...nel.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 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.

> +
>         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
>