[cdi-devel] [PATCH 3/5] e1000: Initialise status field in Rx Descriptors

[Kevin Wolf <kevin@xxxxxxxxxx>]

Checking whether bit 0 has been set in the status field only works for
determining whether a descriptor has been used by the NIC if the bit is
properly cleared before handing it to the device.

Signed-off-by: Kevin Wolf <kevin@xxxxxxxxxx>
---
 e1000/device.c     | 4 ++++
 include/cdi/misc.h | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/e1000/device.c b/e1000/device.c
index ac9bc2d..cf5bc81 100644
--- a/e1000/device.c
+++ b/e1000/device.c
@@ -384,6 +384,7 @@ static void reset_nic(struct e1000_device* netcard)
     for (i = 0; i < RX_BUFFER_NUM; i++) {
         netcard->rx_desc[i].length = RX_BUFFER_SIZE;
         netcard->rx_desc[i].buffer = PHYS(netcard, rx_buffer[i * RX_BUFFER_SIZE]);
+        netcard->rx_desc[i].status = 0;
 
 #ifdef DEBUG
         printf("e1000: [%d] Rx: Buffer @ phys %08llx, Desc @ phys %08x\n",
@@ -626,6 +627,9 @@ static void e1000_handle_interrupt(struct cdi_device* device)
                 &netcard->rx_buffer[netcard->rx_cur_buffer * RX_BUFFER_SIZE],
                 size);
 
+            cdi_barrier();
+            netcard->rx_desc[netcard->rx_cur_buffer].status = 0;
+
             netcard->rx_cur_buffer++;
             netcard->rx_cur_buffer %= RX_BUFFER_NUM;
         }
diff --git a/include/cdi/misc.h b/include/cdi/misc.h
index 9676b4a..2f0f500 100644
--- a/include/cdi/misc.h
+++ b/include/cdi/misc.h
@@ -25,6 +25,8 @@
 extern "C" {
 #endif
 
+#define cdi_barrier() do { asm volatile("" ::: "memory"); } while(0)
+
 /**
  * Registiert einen neuen IRQ-Handler.
  *
-- 
2.1.4