linux-kernel - Re: [PATCH] toshiba_acpi: Fix keyboard backight sysfs entries not being updated

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Message-ID: <20151120233956.GF7413@malice.jf.intel.com>
Date:	Fri, 20 Nov 2015 15:39:56 -0800
From:	Darren Hart <dvhart@...radead.org>
To:	Azael Avalos <coproscefalo@...il.com>
Cc:	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] toshiba_acpi: Fix keyboard backight sysfs entries not
 being updated

On Mon, Nov 16, 2015 at 12:59:31PM -0700, Azael Avalos wrote:
> Certain Toshiba models with the second generation keyboard backlight
> (type 2) do not generate the keyboard backlight changed event (0x92),
> and thus, the sysfs entries are never being updated.
> 
> This patch adds a workquee and a global boolean variable to address
> the issue.
> 
> For those models that do generate the event, the sysfs entries are
> being updated via the *notify function and the boolean is set to
> true to avoid a second call to update the entries.
> 
> For those models that do not generate the event, the workquee is
> used to update the sysfs entries and also to emulate the event via
> netlink, to make userspace aware of such change.

Thanks Azael,

Rather than ask you to wait while I research workqueues and their use more, what
is it about this task that requires a workqueue? Why can we not call what's in
the workqueue below directly from the kbd_backlight_mode_store sysfs write
callback?

> 
> Signed-off-by: Azael Avalos <coproscefalo@...il.com>
> ---
>  drivers/platform/x86/toshiba_acpi.c | 45 +++++++++++++++++++++++++++++++++----
>  1 file changed, 41 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c
> index c013029..3e2702b 100644
> --- a/drivers/platform/x86/toshiba_acpi.c
> +++ b/drivers/platform/x86/toshiba_acpi.c
> @@ -200,6 +200,7 @@ struct toshiba_acpi_dev {
>  	unsigned int sysfs_created:1;
>  	unsigned int special_functions;
>  
> +	bool kbd_event_generated;
>  	bool kbd_led_registered;
>  	bool illumination_led_registered;
>  	bool eco_led_registered;
> @@ -516,6 +517,7 @@ static void toshiba_kbd_illum_available(struct toshiba_acpi_dev *dev)
>  
>  	dev->kbd_illum_supported = 0;
>  	dev->kbd_led_registered = false;
> +	dev->kbd_event_generated = false;
>  
>  	if (!sci_open(dev))
>  		return;
> @@ -1535,6 +1537,24 @@ static const struct backlight_ops toshiba_backlight_data = {
>  	.update_status  = set_lcd_status,
>  };
>  
> +/* Keyboard backlight work */
> +static void toshiba_acpi_kbd_bl_work(struct work_struct *work)
> +{
> +	struct acpi_device *acpi_dev = toshiba_acpi->acpi_dev;
> +
> +	/* Update the sysfs entries */
> +	if (sysfs_update_group(&acpi_dev->dev.kobj,
> +			       &toshiba_attr_group))
> +		pr_err("Unable to update sysfs entries\n");
> +
> +	/* Emulate the keyboard backlight event */
> +	acpi_bus_generate_netlink_event(acpi_dev->pnp.device_class,
> +					dev_name(&acpi_dev->dev),
> +					0x92, 0);
> +}
> +
> +static DECLARE_WORK(kbd_bl_work, toshiba_acpi_kbd_bl_work);
> +
>  /*
>   * Sysfs files
>   */
> @@ -1634,6 +1654,24 @@ static ssize_t kbd_backlight_mode_store(struct device *dev,
>  			return ret;
>  
>  		toshiba->kbd_mode = mode;
> +
> +		/*
> +		 * Some laptop models with the second generation backlit
> +		 * keyboard (type 2) do not generate the keyboard backlight
> +		 * changed event (0x92), and thus, the driver will never update
> +		 * the sysfs entries.
> +		 *
> +		 * The event is generated right when changing the keyboard
> +		 * backlight mode and the *notify function will set the
> +		 * kbd_event_generated to true.
> +		 *
> +		 * In case the event is not generated, schedule the keyboard
> +		 * backlight work to update the sysfs entries and emulate the
> +		 * event via genetlink.
> +		 */
> +		if (toshiba->kbd_type == 2 &&
> +		    !toshiba_acpi->kbd_event_generated)
> +			schedule_work(&kbd_bl_work);
>  	}
>  
>  	return count;
> @@ -2760,7 +2798,6 @@ error:
>  static void toshiba_acpi_notify(struct acpi_device *acpi_dev, u32 event)
>  {
>  	struct toshiba_acpi_dev *dev = acpi_driver_data(acpi_dev);
> -	int ret;
>  
>  	switch (event) {
>  	case 0x80: /* Hotkeys and some system events */
> @@ -2790,10 +2827,10 @@ static void toshiba_acpi_notify(struct acpi_device *acpi_dev, u32 event)
>  		pr_info("SATA power event received %x\n", event);
>  		break;
>  	case 0x92: /* Keyboard backlight mode changed */
> +		toshiba_acpi->kbd_event_generated = true;
>  		/* Update sysfs entries */
> -		ret = sysfs_update_group(&acpi_dev->dev.kobj,
> -					 &toshiba_attr_group);
> -		if (ret)
> +		if (sysfs_update_group(&acpi_dev->dev.kobj,
> +				       &toshiba_attr_group))
>  			pr_err("Unable to update sysfs entries\n");
>  		break;
>  	case 0x85: /* Unknown */
> -- 
> 2.6.3
> 
> 

-- 
Darren Hart
Intel Open Source Technology Center
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