Commit f4e41345 authored by Cindy H Kao's avatar Cindy H Kao Committed by Inaky Perez-Gonzalez

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
......@@ -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);
__i2400m_dev_stop(i2400m);
result = __i2400m_dev_start(i2400m,
I2400M_BRI_SOFT | I2400M_BRI_MAC_REINIT);
if (result < 0) {
rmb();
if (i2400m->updown) {
__i2400m_dev_stop(i2400m);
i2400m->updown = 0;
wmb(); /* see i2400m->updown's documentation */
dev_err(dev, "%s: cannot start the device: %d\n",
reason, result);
result = -EUCLEAN;
}
out_unlock:
if (i2400m->alive) {
result = __i2400m_dev_start(i2400m,
I2400M_BRI_SOFT | I2400M_BRI_MAC_REINIT);
if (result < 0) {
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");
}
}
}
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);
......
......@@ -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;
};
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment