netdev - Re: [PATCH v3] sis900: Fix the tx queue timeout issue

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Date:	Fri, 02 Aug 2013 15:04:00 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	bhutchings@...arflare.com
Cc:	kda@...ux-powerpc.org, venza@...wnhat.org, B38611@...escale.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH v3] sis900: Fix the tx queue timeout issue

From: Ben Hutchings <bhutchings@...arflare.com>
Date: Fri, 2 Aug 2013 21:18:55 +0200

> This looks reasonable.  It looks like link changes now work like this:
> 
> 1. When sis900_timer() detects link-down, it calls netif_carrier_off()
> but does not clear autong_complete.
> 2. When sis900_timer() detects link-up, it calls sis900_check_mode()
> which restarts autonegotiation and clears autong_complete.
> 3. sis900_timer() will now call sis900_read_mode().  When that detects
> link-up, it sets autong_complete and calls netif_carrier_on().
> 
> This patch has moved the call to netif_carrier_on() from step 2 to step
> 3.  However, I don't understand why autonegotiation is restarted in step
> 2.  When autonegotiation is enabled, the PHY should not indicate link-up
> until it has completed.  Perhaps this is a necessary workaround for a
> hardware bug.  Otherwise it's a waste of time.

Agreed, if the PHY was configured to use autonegotiation, getting a link
up event afterwards implies that autonegotiation is complete.

In any event, I'm going to apply this patch anyways because it is far and
above a significant move forward.
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