405GP network receive problem

I am debugging a custom board design based on the 405GP and have a problem
receiving lots of TCP/IP traffic (like FTP).  We're using a 2.4 kernel based
on Monta Vista's CDK 1.2.  UDP traffic (like TFTP) works very well, but it
doesn't ever have back-to-back receives, typically.  The problem occurs
at both 10mbit and 100Mbit.

I have narrowed the problem down (using ttcp) to the following:

During back-to-back receives (within microseconds) of two large (1500 bytes)
TCP packets, the second packet is usually dropped by the 405GP.  When I
check ifconfig statistics, it shows the 1 lost packet, but also shows 2
framing errors.

Has anyone else seen this type of problem with the 405GP or does anyone
know what the problem might be?

Thanks,
John
------------------------------
John Cagle [off-list ref]

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John Cagle wrote:

I am debugging a custom board design based on the 405GP and have a problem
receiving lots of TCP/IP traffic (like FTP).  We're using a 2.4 kernel based
on Monta Vista's CDK 1.2.  UDP traffic (like TFTP) works very well, but it
doesn't ever have back-to-back receives, typically.  The problem occurs
at both 10mbit and 100Mbit.

I have narrowed the problem down (using ttcp) to the following:

During back-to-back receives (within microseconds) of two large (1500 bytes)
TCP packets, the second packet is usually dropped by the 405GP.  When I
check ifconfig statistics, it shows the 1 lost packet, but also shows 2
framing errors.

Has anyone else seen this type of problem with the 405GP or does anyone
know what the problem might be?

Thanks,
John

John,

the ethernet driver in hhl 1.2 had only one tx & rx buffer and we where
not flushing the cache properly.  I have included the latest driver &
header file.

regards,

armin

----- Original Message -----
From: "John Cagle" <jcagle@kernel.org>
To: <redacted>
Sent: Friday, June 29, 2001 10:46 AM
Subject: 405GP network receive problem

I am debugging a custom board design based on the 405GP and have a problem
receiving lots of TCP/IP traffic (like FTP).  We're using a 2.4 kernel

based

on Monta Vista's CDK 1.2.  UDP traffic (like TFTP) works very well, but it
doesn't ever have back-to-back receives, typically.  The problem occurs
at both 10mbit and 100Mbit.

I have narrowed the problem down (using ttcp) to the following:

During back-to-back receives (within microseconds) of two large (1500

bytes)

TCP packets, the second packet is usually dropped by the 405GP.  When I
check ifconfig statistics, it shows the 1 lost packet, but also shows 2
framing errors.

Has anyone else seen this type of problem with the 405GP or does anyone
know what the problem might be?

Thanks,
John
------------------------------
John Cagle [off-list ref]

This can happen if the 405gp MAC is in full-duplex mode, but the other side
is in half-duplex.  The second packet could be corrupted by 405gp sending
TCP acknowledgments without listening for traffic first.

The function in the ppc405_enet driver determines half/full duplex is
ppc405_phy_duplex.  If reading PHY_BMCR does not give the correct duplex
setting, you can try the following.

 -Raymond


static int
ppc405_phy_duplex(void)
{
        int duplex = HALF;          /* Assume HALF */
        unsigned short anlpar = 0x0;

        if (ppc405_phy_read(PHY_ANLPAR,&anlpar)) {
                printk(KERN_ERR "phy duplex read failed \n\r");
                ppc405_phy_dump(KERN_ERR);
        }

        if ((anlpar & (PHY_ANLPAR_10FD | PHY_ANLPAR_TXFD)) != 0)
                duplex = FULL;

        return (duplex);
}


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