Changeset 297 for soft/giet_vm/giet_drivers/tty_driver.c

Timestamp:

Mar 28, 2014, 10:48:51 AM (11 years ago)

Author:

alain

Message:

Bug fix in both _tty_rx_isr() and _bdv_isr():
The ISR must do nothing it the status indicates that
there is no pending ISR.

File:

• soft/giet_vm/giet_drivers/tty_driver.c (modified) (3 diffs)

soft/giet_vm/giet_drivers/tty_driver.c

@@ -170 +170 @@
 
 ///////////////////////////////////////////////////////////////////////////////////
-// This ISR handles the IRQ signaling that the RX buffer is full.
+// This ISR handles the IRQ signaling that the RX buffer is not empty.
 // IT can be an HWI or an SWI.
-// There is one single multi_tty component controling all channels.
 // There is one communication buffer _tty_rx_buf[i] and one synchronisation
 // variable _tty_rx_full[i] per channel.
-// A character is lost if the buffer is full when the ISR is executed.
+// Does nothing if the TTY_RX buffer is empty, or if the kernel buffer is full
+// when the ISR is called.
 ///////////////////////////////////////////////////////////////////////////////////
 void _tty_rx_isr( unsigned int irq_type,   // HWI / WTI
@@ -183 +183 @@
     unsigned int cluster_xy = _get_procid() / NB_PROCS_MAX;
 
-    if ( irq_type == IRQ_TYPE_WTI )   // reset SWI in XCU if required
+    // get TTY status
+    unsigned int status = _tty_get_register( channel, TTY_STATUS );
+
+    // check both TTY status and kernel buffer status:
+    // does nothing if kernel buffer full or tty_buffer empty
+    if ( ((status & 0x1) == 0) || 
+         (_tty_rx_full[channel] != 0) )  return;
+ 
+    // reset WTI in XCU if WTI type
+    if ( irq_type == IRQ_TYPE_WTI ) 
     {
         unsigned int value;
         _xcu_get_wti_value( cluster_xy, irq_id, &value );
     }
-      
-    // get character and reset TTY IRQ
-    _tty_rx_buf[channel] = _tty_get_register( channel, TTY_READ ); 
+
+    // transfer character to kernel buffer and acknowledge TTY IRQ 
+    _tty_rx_buf[channel]  = _tty_get_register( channel, TTY_READ ); 
+
+    // set kernel buffer status
+    asm volatile( "sync" );
+    _tty_rx_full[channel] = 1;
 
 #if GIET_DEBUG_IRQS  // we don't take the TTY lock to avoid deadlock
@@ -209 +222 @@
 #endif
 
-    // signals character available 
-    _tty_rx_full[channel] = 1;
 }