wimax/i2400m: add the error recovery mechanism on TX path

This patch adds an error recovery mechanism on TX path.
The intention is to bring back the device to some known state
whenever TX sees -110 (-ETIMEOUT) on copying the data to the HW FIFO.

The TX failure could mean a device bus stuck or function stuck, so
the current error recovery implementation is to trigger a bus reset
and expect this can bring back the device.

Since the TX work is done in a thread context, there may be a queue of TX works
already that all hit the -ETIMEOUT error condition because the device has
somewhat stuck already. We don't want any consecutive bus resets simply because
multiple TX works in the queue all hit the same device erratum, the flag
"error_recovery" is introduced to denote if we are ready for taking any
error recovery. See @error_recovery doc in i2400m.h.

Signed-off-by: Cindy H Kao <cindy.h.kao@intel.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h
index ad8e6a3..7a9c2c5 100644
--- a/drivers/net/wimax/i2400m/i2400m.h
+++ b/drivers/net/wimax/i2400m/i2400m.h
@@ -545,6 +545,15 @@ struct i2400m_barker_db;
  *	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().
+ *
+ * @error_recovery: flag to denote if we are ready to take an error recovery.
+ *	0 for ready to take an error recovery; 1 for not ready. It is
+ *	initialized to 1 while probe() since we don't tend to take any error
+ *	recovery during probe(). It is decremented by 1 whenever dev_start()
+ *	succeeds to indicate we are ready to take error recovery from now on.
+ *	It is checked every time we wanna schedule an error recovery. If an
+ *	error recovery is already in place (error_recovery was set 1), we
+ *	should not schedule another one until the last one is done.
  */
 struct i2400m {
 	struct wimax_dev wimax_dev;	/* FIRST! See doc */
@@ -625,6 +634,10 @@ struct i2400m {
 
 	/* if the device is expected to be alive */
 	unsigned alive;
+
+	/* 0 if we are ready for error recovery; 1 if not ready  */
+	atomic_t error_recovery;
+
 };
 
 
@@ -847,6 +860,7 @@ void i2400m_put(struct i2400m *i2400m)
 extern int i2400m_dev_reset_handle(struct i2400m *, const char *);
 extern int i2400m_pre_reset(struct i2400m *);
 extern int i2400m_post_reset(struct i2400m *);
+extern void i2400m_error_recovery(struct i2400m *);
 
 /*
  * _setup()/_release() are called by the probe/disconnect functions of