Re: [RFC] b43: A patch for control of the radio LED using rfkill

[Michael Buesch <mb@bu3sch.de>]

On Thursday 18 September 2008 07:07:51 Larry Finger wrote:
> Index: wireless-testing/drivers/net/wireless/b43/rfkill.c
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/b43/rfkill.c
> +++ wireless-testing/drivers/net/wireless/b43/rfkill.c
> @@ -44,13 +44,11 @@ static bool b43_is_hw_radio_enabled(stru
>  	return 0;
>  }
>  
> -/* The poll callback for the hardware button. */
> -static void b43_rfkill_poll(struct input_polled_dev *poll_dev)
> +static void b43_rfkill_update(struct b43_wldev *dev)
>  {
> -	struct b43_wldev *dev = poll_dev->private;
>  	struct b43_wl *wl = dev->wl;
>  	bool enabled;
> -	bool report_change = 0;
> +	struct b43_rfkill *rfk = &(dev->wl->rfkill);
>  
>  	mutex_lock(&wl->mutex);
>  	if (unlikely(b43_status(dev) < B43_STAT_INITIALIZED)) {
> @@ -60,18 +58,40 @@ static void b43_rfkill_poll(struct input
>  	enabled = b43_is_hw_radio_enabled(dev);
>  	if (unlikely(enabled != dev->radio_hw_enable)) {
>  		dev->radio_hw_enable = enabled;
> -		report_change = 1;
>  		b43info(wl, "Radio hardware status changed to %s\n",
>  			enabled ? "ENABLED" : "DISABLED");
> +		if (!enabled)
> +			rfkill_force_state(rfk->rfkill,
> +					   RFKILL_STATE_HARD_BLOCKED);
> +		else {
> +			if (!dev->phy.radio_on)
> +				rfkill_force_state(rfk->rfkill,
> +						   RFKILL_STATE_SOFT_BLOCKED);
> +			else
> +				rfkill_force_state(rfk->rfkill,
> +						   RFKILL_STATE_UNBLOCKED);
> +		}
>  	}
>  	mutex_unlock(&wl->mutex);

Can rfkill_force_state recurse into b43_rfkill_soft_toggle()?
input_report_key could do this in the past (Dunno if that's still true now),
so that's why it's done outside of the lock to avoid deadlocks.

Also keep in mind that N and LP(?) devices report state through interrupt.

> +}
>  
> -	/* send the radio switch event to the system - note both a key press
> -	 * and a release are required */
> -	if (unlikely(report_change)) {
> -		input_report_key(poll_dev->input, KEY_WLAN, 1);
> -		input_report_key(poll_dev->input, KEY_WLAN, 0);
> -	}
> +static void b43_rfkill_poll(unsigned long data)
> +{
> +	struct b43_rfkill *rfkill = (struct b43_rfkill *)data;
> +	schedule_work(&rfkill->poll_queue);
> +}
> +
> +static void b43_rfkill_work(struct work_struct *work)
> +{
> +	struct b43_rfkill *rfk = container_of(work, struct b43_rfkill,
> +					      poll_queue);
> +	struct b43_wl *wl = container_of(rfk, struct b43_wl, rfkill);
> +	struct b43_wldev *dev = wl->current_dev;
> +
> +	b43_rfkill_update(dev);
> +	rfk->poll_timer.function = b43_rfkill_poll;
> +	rfk->poll_timer.expires = round_jiffies(jiffies + HZ);
> +	add_timer(&rfk->poll_timer);
>  }

Why not using delayed work instead of reinventing the wheel?
Also please schedule it on the mac80211 workqueue to avoid possible
deadlocks with the networking core.

>  /* Called when the RFKILL toggled in software. */
> @@ -141,48 +161,23 @@ void b43_rfkill_init(struct b43_wldev *d
>  	rfk->rfkill->toggle_radio = b43_rfkill_soft_toggle;
>  	rfk->rfkill->user_claim_unsupported = 1;
>  
> -	rfk->poll_dev = input_allocate_polled_device();
> -	if (!rfk->poll_dev) {
> -		rfkill_free(rfk->rfkill);
> -		goto err_freed_rfk;
> -	}
> -
> -	rfk->poll_dev->private = dev;
> -	rfk->poll_dev->poll = b43_rfkill_poll;
> -	rfk->poll_dev->poll_interval = 1000; /* msecs */
> -
> -	rfk->poll_dev->input->name = rfk->name;
> -	rfk->poll_dev->input->id.bustype = BUS_HOST;
> -	rfk->poll_dev->input->id.vendor = dev->dev->bus->boardinfo.vendor;
> -	rfk->poll_dev->input->evbit[0] = BIT(EV_KEY);
> -	set_bit(KEY_WLAN, rfk->poll_dev->input->keybit);
> -
>  	err = rfkill_register(rfk->rfkill);
>  	if (err)
> -		goto err_free_polldev;
> +		goto err_free_rfk;
>  
> -#ifdef CONFIG_RFKILL_INPUT_MODULE
> -	/* B43 RF-kill isn't useful without the rfkill-input subsystem.
> -	 * Try to load the module. */
> -	err = request_module("rfkill-input");
> -	if (err)
> -		b43warn(wl, "Failed to load the rfkill-input module. "
> -			"The built-in radio LED will not work.\n");
> -#endif /* CONFIG_RFKILL_INPUT */
> +	rfk->registered = 1;
>  
> -	err = input_register_polled_device(rfk->poll_dev);
> -	if (err)
> -		goto err_unreg_rfk;
> +	INIT_WORK(&rfk->poll_queue, b43_rfkill_work);
>  
> -	rfk->registered = 1;
> +	init_timer(&rfk->poll_timer);
> +	rfk->poll_timer.function = b43_rfkill_poll;
> +	rfk->poll_timer.expires = round_jiffies(jiffies + HZ);
> +	rfk->poll_timer.data = (unsigned long)rfk;
> +	add_timer(&rfk->poll_timer);
>  
>  	return;
> -err_unreg_rfk:
> -	rfkill_unregister(rfk->rfkill);
> -err_free_polldev:
> -	input_free_polled_device(rfk->poll_dev);
> -	rfk->poll_dev = NULL;
> -err_freed_rfk:
> +err_free_rfk:
> +	rfkill_free(rfk->rfkill);
>  	rfk->rfkill = NULL;
>  out_error:
>  	rfk->registered = 0;
> @@ -197,9 +192,8 @@ void b43_rfkill_exit(struct b43_wldev *d
>  		return;
>  	rfk->registered = 0;
>  
> -	input_unregister_polled_device(rfk->poll_dev);
> +	del_timer(&rfk->poll_timer);
> +

cancel the work. I'm not sure whether to do it here, however.
One must take care to avoid deadlocks for wl->mutex.
I don't know from the top of my head whether b43_rfkill_exit is called
with the mutex locked or not. However, in case it is, dropping and
reaquireing the lock is not an option.

>  	rfkill_unregister(rfk->rfkill);
> -	input_free_polled_device(rfk->poll_dev);
> -	rfk->poll_dev = NULL;
>  	rfk->rfkill = NULL;
>  }
> Index: wireless-testing/drivers/net/wireless/b43/rfkill.h
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/b43/rfkill.h
> +++ wireless-testing/drivers/net/wireless/b43/rfkill.h
> @@ -7,14 +7,14 @@ struct b43_wldev;
>  #ifdef CONFIG_B43_RFKILL
>  
>  #include <linux/rfkill.h>
> -#include <linux/input-polldev.h>
> -
>  
>  struct b43_rfkill {
>  	/* The RFKILL subsystem data structure */
>  	struct rfkill *rfkill;
> -	/* The poll device for the RFKILL input button */
> -	struct input_polled_dev *poll_dev;
> +	/* The timer list for the RFKILL polling */
> +	struct timer_list poll_timer;
> +	/* Workqueue for the RFKILL polling */
> +	struct work_struct poll_queue;
>  	/* Did initialization succeed? Used for freeing. */
>  	bool registered;
>  	/* The unique name of this rfkill switch */

-- 
Greetings Michael.