Changeset 577

Timestamp:

May 21, 2015, 3:04:21 PM (10 years ago)

Author:

bellefin

Message:

Improve hba driver

File:

• soft/giet_vm/giet_drivers/hba_driver.h (modified) (2 diffs)

soft/giet_vm/giet_drivers/hba_driver.h

@@ -17 +17 @@
 //
 // 3. The "command list" can contain up to 32 independant commands, posted
-//    by different user tasks. These independant transfers are handled 
-//    by the HBA device in the same order as they have been written by the
-//    driver(s) in the command list. There is no global lock protecting the
-//    the HBA device, but the command list being a shared structure, the driver
-//    must use an atomic_increment() to get a slot in the command list,
-//    and increment the write pointer.
+//    by different user tasks. These independant transfers are handled by
+//    the HBA device. The command list being a shared structure, the driver
+//    must use a lock to get a slot in the command list (except in boot mode
+//    when only one processor uses the HBA device). This slot is then 
+//    allocated to the task until the command is completed. 
 //
 // 4. This driver implements two operating mode: 
@@ -35 +34 @@
 //    that is statically routed to processor P[x_io,y_io,0] in cluster_io. 
 //    The associated global HBA_ISR send a WAKUP WTI to all tasks that have
-//    a completed command. This HBA_ISR uses a read pointer on the command 
-//    to identify the first expected command completion. The incrementation 
-//    of this read pointer does not require atomic_increment as there is
-//    no concurrent access for this pointer. 
+//    a completed active command. In order to know which commands expect
+//    completion, the HBA_ISR uses the _hba_active_cmd table which indicates
+//    currently active commands (in descheduling mode only).
 //
 // The SEG_IOC_BASE virtual address must be defined in the hard_config.h file.