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Commit f4e41345 authored by Cindy H Kao's avatar Cindy H Kao Committed by Inaky Perez-Gonzalez
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wimax/i2400m: fix for missed reset events if triggered by dev_reset_handle() 



The problem is only seen on SDIO interface since on USB, a bus reset would
really re-probe the driver, but on SDIO interface, a bus reset will not
re-enumerate the SDIO bus, so no driver re-probe is happening. Therefore,
on SDIO interface, the reset event should be still detected and handled by
dev_reset_handle().

Problem description:
Whenever a reboot barker is received during operational mode (i2400m->boot_mode == 0),
dev_reset_handle() is invoked to handle that function reset event.
dev_reset_handle() then sets the flag i2400m->boot_mode to 1 indicating the device is
back to bootmode before proceeding to dev_stop() and dev_start().
If dev_start() returns failure, a bus reset is triggered by dev_reset_handle().

The flag i2400m->boot_mode then remains 1 when the second reboot barker arrives.
However the interrupt service routine i2400ms_rx() instead of invoking dev_reset_handle()
to handle that reset event, it filters out that boot event to bootmode because it sees
the flag i2400m->boot_mode equal to 1.

The fix:
Maintain the flag i2400m->boot_mode within dev_reset_handle() and set the flag
i2400m->boot_mode to 1 when entering dev_reset_handle(). It remains 1
until the dev_reset_handle() issues a bus reset. ie: the bus reset is
taking place just like it happens for the first time during operational mode.

To denote the actual device state and the state we expect, a flag i2400m->alive
is introduced in addition to the existing flag i2400m->updown.
It's maintained with the same way for i2400m->updown but instead of reflecting
the actual state like i2400m->updown does, i2400m->alive maintains the state
we expect. i2400m->alive is set 1 just like whenever i2400m->updown is set 1.
Yet i2400m->alive remains 1 since we expect the device to be up all the time
until the driver is removed. See the doc for @alive in i2400m.h.

An enumeration I2400M_BUS_RESET_RETRIES is added to define the maximum number of
bus resets that a device reboot can retry.

A counter i2400m->bus_reset_retries is added to track how many bus resets
have been retried in one device reboot. If I2400M_BUS_RESET_RETRIES bus resets
were retried in this boot, we give up any further retrying so the device would enter
low power state. The counter i2400m->bus_reset_retries is incremented whenever
dev_reset_handle() is issuing a bus reset and is cleared to 0 when dev_start() is
successfully done, ie: a successful reboot.

Signed-off-by: default avatarCindy H Kao <cindy.h.kao@intel.com>
parent 49d72df3

drivers/net/wimax/i2400m/driver.c

+52 −16
Original line number Diff line number Diff line
@@ -436,7 +436,8 @@ int i2400m_dev_start(struct i2400m *i2400m, enum i2400m_bri bm_flags) 
		result = __i2400m_dev_start(i2400m, bm_flags);

		if (result >= 0) {

			i2400m->updown = 1;

			wmb();	/* see i2400m->updown's documentation */

			i2400m->alive = 1;

			wmb();/* see i2400m->updown and i2400m->alive's doc */

		}

	}

	mutex_unlock(&i2400m->init_mutex);
@@ -497,7 +498,8 @@ void i2400m_dev_stop(struct i2400m *i2400m) 
	if (i2400m->updown) {

		__i2400m_dev_stop(i2400m);

		i2400m->updown = 0;

		wmb();	/* see i2400m->updown's documentation  */

		i2400m->alive = 0;

		wmb();	/* see i2400m->updown and i2400m->alive's doc */

	}

	mutex_unlock(&i2400m->init_mutex);

}
@@ -669,6 +671,9 @@ void __i2400m_dev_reset_handle(struct work_struct *ws) 


	d_fnstart(3, dev, "(ws %p i2400m %p reason %s)\n", ws, i2400m, reason);



	i2400m->boot_mode = 1;

	wmb();		/* Make sure i2400m_msg_to_dev() sees boot_mode */



	result = 0;

	if (mutex_trylock(&i2400m->init_mutex) == 0) {

		/* We are still in i2400m_dev_start() [let it fail] or
@@ -679,32 +684,62 @@ void __i2400m_dev_reset_handle(struct work_struct *ws) 
		complete(&i2400m->msg_completion);

		goto out;

	}

	if (i2400m->updown == 0)  {

		dev_info(dev, "%s: device is down, doing nothing\n", reason);

		goto out_unlock;

	}



	dev_err(dev, "%s: reinitializing driver\n", reason);

	rmb();

	if (i2400m->updown) {

		__i2400m_dev_stop(i2400m);

		i2400m->updown = 0;

		wmb();		/* see i2400m->updown's documentation  */

	}



	if (i2400m->alive) {

		result = __i2400m_dev_start(i2400m,

				    I2400M_BRI_SOFT | I2400M_BRI_MAC_REINIT);

		if (result < 0) {

		i2400m->updown = 0;

		wmb();		/* see i2400m->updown's documentation  */

			dev_err(dev, "%s: cannot start the device: %d\n",

				reason, result);

			result = -EUCLEAN;

			if (atomic_read(&i2400m->bus_reset_retries)

					>= I2400M_BUS_RESET_RETRIES) {

				result = -ENODEV;

				dev_err(dev, "tried too many times to "

					"reset the device, giving up\n");

			}

		}

	}

out_unlock:



	if (i2400m->reset_ctx) {

		ctx->result = result;

		complete(&ctx->completion);

	}

	mutex_unlock(&i2400m->init_mutex);

	if (result == -EUCLEAN) {

		/*

		 * We come here because the reset during operational mode

		 * wasn't successully done and need to proceed to a bus

		 * reset. For the dev_reset_handle() to be able to handle

		 * the reset event later properly, we restore boot_mode back

		 * to the state before previous reset. ie: just like we are

		 * issuing the bus reset for the first time

		 */

		i2400m->boot_mode = 0;

		wmb();



		atomic_inc(&i2400m->bus_reset_retries);

		/* ops, need to clean up [w/ init_mutex not held] */

		result = i2400m_reset(i2400m, I2400M_RT_BUS);

		if (result >= 0)

			result = -ENODEV;

	} else {

		rmb();

		if (i2400m->alive) {

			/* great, we expect the device state up and

			 * dev_start() actually brings the device state up */

			i2400m->updown = 1;

			wmb();

			atomic_set(&i2400m->bus_reset_retries, 0);

		}

	}

out:

	i2400m_put(i2400m);
@@ -729,8 +764,6 @@ void __i2400m_dev_reset_handle(struct work_struct *ws) 
 */

int i2400m_dev_reset_handle(struct i2400m *i2400m, const char *reason)

{

	i2400m->boot_mode = 1;

	wmb();		/* Make sure i2400m_msg_to_dev() sees boot_mode */

	return i2400m_schedule_work(i2400m, __i2400m_dev_reset_handle,

				    GFP_ATOMIC, &reason, sizeof(reason));

}
@@ -803,6 +836,9 @@ void i2400m_init(struct i2400m *i2400m) 


	mutex_init(&i2400m->init_mutex);

	/* wake_tx_ws is initialized in i2400m_tx_setup() */

	atomic_set(&i2400m->bus_reset_retries, 0);



	i2400m->alive = 0;

}

EXPORT_SYMBOL_GPL(i2400m_init);

drivers/net/wimax/i2400m/i2400m.h

+34 −0
Original line number Diff line number Diff line
@@ -177,6 +177,11 @@ enum { 
	I2400M_BM_ACK_BUF_SIZE = 256,

};



enum {

	/* Maximum number of bus reset can be retried */

	I2400M_BUS_RESET_RETRIES = 3,

};



/**

 * struct i2400m_poke_table - Hardware poke table for the Intel 2400m

 *
@@ -517,6 +522,29 @@ struct i2400m_barker_db; 
 *     same.

 *

 * @pm_notifier: used to register for PM events

 *

 * @bus_reset_retries: counter for the number of bus resets attempted for

 *	this boot. It's not for tracking the number of bus resets during

 *	the whole driver life cycle (from insmod to rmmod) but for the

 *	number of dev_start() executed until dev_start() returns a success

 *	(ie: a good boot means a dev_stop() followed by a successful

 *	dev_start()). dev_reset_handler() increments this counter whenever

 *	it is triggering a bus reset. It checks this counter to decide if a

 *	subsequent bus reset should be retried. dev_reset_handler() retries

 *	the bus reset until dev_start() succeeds or the counter reaches

 *	I2400M_BUS_RESET_RETRIES. The counter is cleared to 0 in

 *	dev_reset_handle() when dev_start() returns a success,

 *	ie: a successul boot is completed.

 *

 * @alive: flag to denote if the device *should* be alive. This flag is

 *	everything like @updown (see doc for @updown) except reflecting

 *	the device state *we expect* rather than the actual state as denoted

 *	by @updown. It is set 1 whenever @updown is set 1 in dev_start().

 *	Then the device is expected to be alive all the time

 *	(i2400m->alive remains 1) until the driver is removed. Therefore

 *	all the device reboot events detected can be still handled properly

 *	by either dev_reset_handle() or .pre_reset/.post_reset as long as

 *	the driver presents. It is set 0 along with @updown in dev_stop().

 */

struct i2400m {

	struct wimax_dev wimax_dev;	/* FIRST! See doc */
@@ -591,6 +619,12 @@ struct i2400m { 
	struct i2400m_barker_db *barker;



	struct notifier_block pm_notifier;



	/* counting bus reset retries in this boot */

	atomic_t bus_reset_retries;



	/* if the device is expected to be alive */

	unsigned alive;

};