From f4e413458104210bc29aa5c437882c68b4b20100 Mon Sep 17 00:00:00 2001 From: Cindy H Kao Date: Wed, 7 Apr 2010 19:42:42 -0700 Subject: [PATCH] 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: Cindy H Kao --- drivers/net/wimax/i2400m/driver.c | 68 ++++++++++++++++++++++++++++++--------- drivers/net/wimax/i2400m/i2400m.h | 34 ++++++++++++++++++++ 2 files changed, 86 insertions(+), 16 deletions(-) diff --git a/drivers/net/wimax/i2400m/driver.c b/drivers/net/wimax/i2400m/driver.c index 3a6c8dd..1674dba 100644 --- a/drivers/net/wimax/i2400m/driver.c +++ b/drivers/net/wimax/i2400m/driver.c @@ -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 @@ out: */ 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); diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h index da218b9..ad8e6a3 100644 --- a/drivers/net/wimax/i2400m/i2400m.h +++ b/drivers/net/wimax/i2400m/i2400m.h @@ -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; }; -- 2.7.4