From: Joe Perches <joe@perches.com>
To: David Daney <ddaney.cavm@gmail.com>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
linux-mips@linux-mips.org, David Daney <david.daney@cavium.com>
Subject: Re: [PATCH 1/2] netdev: octeon_mgmt: Correct tx IFG workaround.
Date: Wed, 19 Jun 2013 18:37:19 -0700 [thread overview]
Message-ID: <1371692239.2146.7.camel@joe-AO722> (raw)
In-Reply-To: <51C25ACA.1070907@gmail.com>
On Wed, 2013-06-19 at 18:28 -0700, David Daney wrote:
> On 06/19/2013 06:08 PM, Joe Perches wrote:
> > On Wed, 2013-06-19 at 17:40 -0700, David Daney wrote:
> >> From: David Daney <david.daney@cavium.com>
> >>
> >> The previous fix was still too agressive to meet ieee specs. Increase
> >> to (14, 10).
> > []
> >> diff --git a/drivers/net/ethernet/octeon/octeon_mgmt.c b/drivers/net/ethernet/octeon/octeon_mgmt.c
> > []
> >> @@ -1141,10 +1141,13 @@ static int octeon_mgmt_open(struct net_device *netdev)
> >> /* For compensation state to lock. */
> >> ndelay(1040 * NS_PER_PHY_CLK);
> >>
> >> - /* Some Ethernet switches cannot handle standard
> >> - * Interframe Gap, increase to 16 bytes.
> >> + /* Default Interframe Gaps are too small. Recommended
> >> + * workaround is.
> >> + *
> >> + * AGL_GMX_TX_IFG[IFG1]=14
> >> + * AGL_GMX_TX_IFG[IFG2]=10
> >
> > Why isn't the TX IFG just 96 bit times?
>
> I don't have a full understanding of how the transistors are wired up on
> the chip, so I cannot accurately answer your question. But I can say
> that after I empirically found the previous values to get the thing to
> work, the hardware designers independently found that the values
> supplied in this patch are required to achieve industry standard IFGs
> with this hardware.
For one specific chip or for the Octeon entire family?
next prev parent reply other threads:[~2013-06-20 1:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 0:40 [PATCH 0/2] netdev: octeon_mgmt minor fixes David Daney
2013-06-20 0:40 ` [PATCH 1/2] netdev: octeon_mgmt: Correct tx IFG workaround David Daney
2013-06-20 1:08 ` Joe Perches
2013-06-20 1:28 ` David Daney
2013-06-20 1:37 ` Joe Perches [this message]
2013-06-20 1:47 ` David Daney
2013-06-20 0:40 ` [PATCH 2/2] netdev: octeon_mgmt: Fix structure layout for little-endian David Daney
2013-06-20 9:47 ` David Laight
2013-06-27 10:40 ` Ralf Baechle
2013-06-20 5:13 ` [PATCH 0/2] netdev: octeon_mgmt minor fixes David Miller
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