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From
SubjectRe: More Patches v pre2#2 and showstopper list for 2.0
Date
 - From "Alan Cox" at May 12, 96 10:30:00 pm

> * Networking Show Stoppers Left
> *
[...]
> * o 8390 overrun bug reports.
[...]

The present 8390 code doesn't follow NS's recommended (I should say
required) overrun handling technique. I have updated it to the
procedure described in the updated datasheets. Nat Semic really stress
that not following their recipe is asking for trouble, so perhaps
that is the problem that some people are seeing. Regardless, people
should be setting their windows correctly so their cards don't get
spammed with more than it can handle, and thus overrun all the time.

Let's hope National got it right in the docos this time.... :-)

Paul.

--- /tmp/linux/drivers/net/8390.c Mon May 6 18:41:57 1996
+++ linux/drivers/net/8390.c Thu May 16 02:32:05 1996
@@ -29,6 +29,7 @@
ei_block_input() for eth_io_copy_and_sum().
Paul Gortmaker : exchange static int ei_pingpong for a #define,
also add better Tx error handling.
+ Paul Gortmaker : rewrite Rx overrun handling as per NS specs.


Sources:
@@ -377,6 +378,7 @@
int e8390_base = dev->base_addr;
unsigned char txsr = inb_p(e8390_base+EN0_TSR);
unsigned char tx_was_aborted = txsr & (ENTSR_ABT+ENTSR_FU);
+ struct ei_device *ei_local = (struct ei_device *) dev->priv;

#ifdef VERBOSE_ERROR_DUMP
printk(KERN_DEBUG "%s: transmitter error (%#2x): ", dev->name, txsr);
@@ -398,6 +400,13 @@
if (tx_was_aborted)
ei_tx_intr(dev);

+ /*
+ * Note: NCR reads zero on 16 collisions so we add them
+ * in by hand. Somebody might care...
+ */
+ if (txsr & ENTSR_ABT)
+ ei_local->stat.collisions += 16;
+
}

/* We have finished a transmit: check for errors and then trigger the next
@@ -580,43 +589,76 @@
return;
}

-/* We have a receiver overrun: we have to kick the 8390 to get it started
- again.*/
+/*
+ * We have a receiver overrun: we have to kick the 8390 to get it started
+ * again. Problem is that you have to kick it exactly as NS prescribes in
+ * the updated datasheets, or "the NIC may act in an unpredictable manner."
+ * This includes causing "the NIC to defer indefinitely when it is stopped
+ * on a busy network." Ugh.
+ */
static void ei_rx_overrun(struct device *dev)
{
int e8390_base = dev->base_addr;
- int reset_start_time = jiffies;
+ unsigned long wait_start_time;
+ unsigned char was_txing, must_resend = 0;
struct ei_device *ei_local = (struct ei_device *) dev->priv;

- /* We should already be stopped and in page0. Remove after testing. */
+ /*
+ * Record whether a Tx was in progress and then issue the
+ * stop command.
+ */
+ was_txing = inb_p(e8390_base+E8390_CMD) & E8390_TRANS;
outb_p(E8390_NODMA+E8390_PAGE0+E8390_STOP, e8390_base+E8390_CMD);

if (ei_debug > 1)
- printk("%s: Receiver overrun.\n", dev->name);
+ printk("%s: Receiver overrun.\n", dev->name);
ei_local->stat.rx_over_errors++;

- /* The old Biro driver does dummy = inb_p( RBCR[01] ); at this point.
- It might mean something -- magic to speed up a reset? A 8390 bug?*/
-
- /* Wait for the reset to complete. This should happen almost instantly,
- but could take up to 1.5msec in certain rare instances. There is no
- easy way of timing something in that range, so we use 'jiffies' as
- a sanity check. */
- while ((inb_p(e8390_base+EN0_ISR) & ENISR_RESET) == 0)
- if (jiffies - reset_start_time > 2*HZ/100) {
- printk("%s: reset did not complete at ei_rx_overrun.\n",
- dev->name);
- NS8390_init(dev, 1);
- return;
- }
-
- /* Remove packets right away. */
+ /*
+ * Wait a full Tx time (1.2ms) + some guard time, NS says 1.6ms total.
+ * Early datasheets said to poll the reset bit, but now they say that
+ * it "is not a reliable indicator and subequently should be ignored."
+ * We wait at least 10ms.
+ */
+ wait_start_time = jiffies;
+ while (jiffies - wait_start_time <= 1*HZ/100)
+ barrier();
+
+ /*
+ * Reset RBCR[01] back to zero as per magic incantation.
+ */
+ outb_p(0x00, e8390_base+EN0_RCNTLO);
+ outb_p(0x00, e8390_base+EN0_RCNTHI);
+
+ /*
+ * See if any Tx was interrupted or not. According to NS, this
+ * step is vital, and skipping it will cause no end of havoc.
+ */
+ if (was_txing) {
+ unsigned char tx_completed = inb_p(e8390_base+EN0_ISR) & (ENISR_TX+ENISR_TX_ERR);
+ if (!tx_completed) must_resend = 1;
+ }
+
+ /*
+ * Have to enter loopback mode and then restart the NIC before
+ * you are allowed to slurp packets up off the ring.
+ */
+ outb_p(E8390_TXOFF, e8390_base + EN0_TXCR);
+ outb_p(E8390_NODMA + E8390_PAGE0 + E8390_START, e8390_base + E8390_CMD);
+
+ /*
+ * Clear the Rx ring of all the debris, and ack the interrupt.
+ */
ei_receive(dev);
-
outb_p(ENISR_OVER, e8390_base+EN0_ISR);
- /* Generic 8390 insns to start up again, same as in open_8390(). */
- outb_p(E8390_NODMA + E8390_PAGE0 + E8390_START, e8390_base + E8390_CMD);
- outb_p(E8390_TXCONFIG, e8390_base + EN0_TXCR); /* xmit on. */
+
+ /*
+ * Leave loopback mode, and resend any packet that got stopped.
+ */
+ outb_p(E8390_TXCONFIG, e8390_base + EN0_TXCR);
+ if (must_resend)
+ outb_p(E8390_NODMA + E8390_PAGE0 + E8390_START + E8390_TRANS, e8390_base + E8390_CMD);
+
}

static struct enet_statistics *get_stats(struct device *dev)

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