Hi All,
A problem was observed in gianfar driver when the interface MTU was modified to
a small value.
FYI Kernel Version : 2.6.32 on PPC.
Like if we change the interface mtu to say 100, ping traffic with size greater
than 450 is failing.
It was observed that packets ( ping requests) going out of that interface are
getting properly fragmented, but the return packets ( ping replies ) are
getting dropped by the interface.
To fix this issue the function gfar_change_mtu() in gianfar.c was modified as
below:
rx_buffer_size is restored to DEFAULT_RX_BUFFER_SIZE as indicated in RED in the
code snippet below
------------------------- CODE SNIPPET BEGIN ----------------------------------
tempsize =
(frame_size & ~(INCREMENTAL_BUFFER_SIZE - 1)) +
INCREMENTAL_BUFFER_SIZE;
if (tempsize < DEFAULT_RX_BUFFER_SIZE )
tempsize = DEFAULT_RX_BUFFER_SIZE;
/* Only stop and start the controller if it isn't already
* stopped, and we changed something */
if ((oldsize != tempsize) && (dev->flags & IFF_UP))
stop_gfar(dev);
priv->rx_buffer_size = tempsize;
dev->mtu = new_mtu;
------------------------- CODE SNIPPET END----------------------------------
If this fix OK? What is the impact of this change on overall behavior?
Best Regards,
- Suresh
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