2015-02-27 16:16:38

by Geert Uytterhoeven

Subject: [PATCH] sh_eth: Fix lost MAC address on kexec

Commit 740c7f31c094703c ("sh_eth: Ensure DMA engines are stopped before
freeing buffers") added a call to sh_eth_reset() to the
sh_eth_set_ringparam() and sh_eth_close() paths.

However, setting the software reset bit(s) in the EDMR register resets
the MAC Address Registers to zero. Hence after kexec, the new kernel
doesn't detect a valid MAC address and assigns a random MAC address,
breaking DHCP.

Set the MAC address again after the reset in sh_eth_dev_exit() to fix
this.

Tested on r8a7740/armadillo (GETHER) and r8a7791/koelsch (FAST_RCAR).

Fixes: 740c7f31c094703c ("sh_eth: Ensure DMA engines are stopped before freeing buffers")
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
drivers/net/ethernet/renesas/sh_eth.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 4da8bd263997a17b..654b48d1e61a3124 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1392,6 +1392,9 @@ static void sh_eth_dev_exit(struct net_device *ndev)
msleep(2); /* max frame time at 10 Mbps < 1250 us */
sh_eth_get_stats(ndev);
sh_eth_reset(ndev);
+
+ /* Set MAC address again */
+ update_mac_address(ndev);
}

/* free Tx skb function */
--
1.9.1

2015-02-28 02:48:50

by Ben Hutchings

Subject: Re: [PATCH] sh_eth: Fix lost MAC address on kexec

On Fri, 2015-02-27 at 17:16 +0100, Geert Uytterhoeven wrote:
> Commit 740c7f31c094703c ("sh_eth: Ensure DMA engines are stopped before
> freeing buffers") added a call to sh_eth_reset() to the
> sh_eth_set_ringparam() and sh_eth_close() paths.
>
> However, setting the software reset bit(s) in the EDMR register resets
> the MAC Address Registers to zero. Hence after kexec, the new kernel
> doesn't detect a valid MAC address and assigns a random MAC address,
> breaking DHCP.
[...]

Sorry about that. This would also affect removing and reloading the
driver as a module, but currently I always have it built in and don't
use kexec.

Ben.