[U-Boot] [PATCH] net: BOOTP retry timeout improvements

[Tom Rini]

On Wed, Aug 06, 2014 at 09:58:12AM -0600, Stephen Warren wrote:
> On 07/25/2014 05:30 PM, Stephen Warren wrote:
> >From: Stephen Warren <swarren at nvidia.com>
> >
> >Currently, the BOOTP code sends out its initial request as soon as the
> >Ethernet driver indicates "link up". If this packet is lost or not
> >replied to for some reason, the code waits for a 1s timeout before
> >retrying. For some reason, such early packets are often lost on my
> >system, so this causes an annoying delay.
> >
> >To optimize this, modify the BOOTP code to have very short timeouts for
> >the first packet transmitted, but gradually increase the timeout each
> >time a timeout occurs. This way, if the first packet is lost, the second
> >packet is transmitted quite quickly and hence the overall delay is low.
> >However, if there's still no response, we don't keep spewing out packets
> >at an insane speed.
> >
> >It's arguably more correct to try and find out why the first packet is
> >lost. However, it seems to disappear inside my Ethenet chip; the TX chip
> >indicates no error during TX (not that it has much in the way of
> >reporting...), yet wireshark on the RX side doesn't see any packet.
> >FWIW, I'm using an ASIX USB Ethernet adapter. Perhaps "link up" is
> >reported too early or based on the wrong condition in HW, and we should
> >add some fixed extra delay into the driver. However, this would slow down
> >every link up event even if it ends up not being needed in some cases.
> >Having BOOTP retry quickly applies the fix/WAR to every possible
> >Ethernet device, and is quite simple to implement, so seems a better
> >solution.
> 
> Joe, Tom,
> 
> Does this patch look OK?

I was a bit worried about this impacting boards that don't have a
problem today but a quick test shows they're still getting the first
reply, so I'm OK with it.  I'll be grabbing things soon.

-- 
Tom
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