Subject: Re: [PATCH 1/2] [v4] net: emac: emac gigabit ethernet controller driver

From: Timur Tabi <[email-masked]>
Date: Tue, 10 May 2016 21:24:55 -0500

Florian Fainelli wrote:
> The Ethernet MAC should be started in ndo_open() and stopped in
> ndo_close(), in between, there are link state changes, but you are not
> supposed to stop or start your Ethernet MAC and its DMA for instance
> during link change, if that is a HW requirement, your HW is pretty funky.

I think the problem is that the current driver seems to be too eager to 
start/stop the MAC.

Please take a look at emac_work_thread_link_check() at 
https://lkml.org/lkml/2016/4/13/670.  Every time the PHY link goes up, 
it does this:

if (phy->link_up) {
	if (netif_carrier_ok(netdev))
		goto link_task_done;

	pm_runtime_get_sync(netdev->dev.parent);
	netif_info(adpt, timer, adpt->netdev, "NIC Link is Up %s\n",
		   speed);

	emac_mac_start(adpt);
	netif_carrier_on(netdev);
	netif_wake_queue(netdev);

The call to emac_mac_start seems wrong to me here.

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