Since, a AT91_EMAC_TUND only happens when the transmitter is unable to transfer the frame in time for a frame to be sent.? It makes sense to RETRY the packet in this condition in the ISR.
Or would this overcomplicate a simple task?
??????????????? ... see below ...
James
---- Attached code snippet ----
/*
?* MAC interrupt handler
?*/
static irqreturn_t at91ether_interrupt(int irq, void *dev_id)
{
...
??????????????? if (intstatus & AT91_EMAC_TCOM) {?????? /* Transmit complete */
??????????????????????????????? /* The TCOM bit is set even if the transmission failed. */
??????????????????????????????? if (intstatus & (AT91_EMAC_TUND | AT91_EMAC_RTRY))
??????????????????????????????????????????????? dev->stats.tx_errors += 1;
??????????????????????????????? if (lp->skb) {
??????????????????????????????????????????????? dev_kfree_skb_irq(lp->skb);
??????????????????????????????????????????????? lp->skb = NULL;
??????????????????????????????????????????????? dma_unmap_single(NULL, lp->skb_physaddr, lp->skb_length, DMA_TO_DEVICE);
??????????????????????????????? }
??????????????????????????????? netif_wake_queue(dev);
??????????????? }
...
---- Alternate approach ----
??????????????????????????????? /* The TCOM bit is set even if the transmission failed. */
??????????????????????????????? if (intstatus & (AT91_EMAC_TUND)) {
??????????????? ??????????????????????????????? /* Set address of the data in the Transmit Address register */
??????????????? ??????????????????????????????? at91_emac_write(AT91_EMAC_TAR, lp->skb_physaddr);
??????????????? ??????????????? ??????????????? /* Set length of the packet in the Transmit Control register */
??????????????????????????????? ??????????????? at91_emac_write(AT91_EMAC_TCR, skb->len);
??????????????????????????????? }
??????????????????????????????? else if (intstatus & (AT91_EMAC_RTRY))
??????????????????????????????????????????????? dev->stats.tx_errors += 1;
...
I do know there needs to be a bit more code then to handle the successful case below this; but, this is enough to understand what I am talking about.? The UNDERRUN error should happen infrequently and in ideal circumstances not happen at all.
----
James Kosin