From: Michael Williamson <michael.williamson@criticallink•com>
To: cyril@ti•com
Cc: "davinci-linux-open-source@linux•davincidsp.com"
<davinci-linux-open-source@linux•davincidsp.com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"tony@atomide•com" <tony@atomide•com>,
"linux-omap@vger•kernel.org" <linux-omap@vger•kernel.org>,
"davem@davemloft•net" <davem@davemloft•net>
Subject: Re: [PATCH v3 00/10] split out emac cpdma and mdio for reuse
Date: Thu, 09 Sep 2010 17:45:44 -0400 [thread overview]
Message-ID: <4C895588.3060500@criticallink.com> (raw)
In-Reply-To: <4C89507E.9040407@ti.com>
On 09/09/2010 05:24 PM, Cyril Chemparathy wrote:
> Hi Mike,
>
> [...]
>> An EMAC soft-reset clobbering the MDIO controller state is a
>> possibility. I will poll TI designers to see if this could be the case.
>
> To test this theory out, I hacked up a crude
> beat-it-to-death-and-see-if-it-breaks kinda patch (attached). This
> tests 10000 mdio read cycles while constantly doing an emac soft-reset.
>
> I ran this on a dm365 evm, and the test didn't raise a single failed read:
>> davinci_mdio davinci_mdio.0: davinci mdio revision 1.4
>> davinci_mdio davinci_mdio.0: detected phy mask fffffffc
>> 10000 test loops completed, 10000 reads ok
>
> The failure in question seems to be limited to the da8xx family (tested
> da830 evm), where:
>> davinci_mdio davinci_mdio.0: davinci mdio revision 1.5
>> davinci_mdio davinci_mdio.0: detected phy mask fffffff1
>> idle triggered!!
>
> The MDIO module upgrade (rev 1.4 -> 1.5) could have something to do with
> this behavior. Even so, I can't explain why this issue wasn't seen on
> da8xx prior to this series. The original code should (at least in
> theory) have sporadically locked up on emac open.
>
I think, if I understand it correctly, that in the previous version of
this code, the emac was reset *prior* to enabling, scanning, and assigning
the associated phy on the MDIO bus. The new implementation sets up and scans
the MDIO bus first, then comes back around to the EMAC second... hits a reset,
and doesn't re-ENABLE the MDIO.
Also, maybe hitting the EMAC reset while the MDIO state machine is up is *bad*, I
seem to recall some text in the user's guide about waiting for the state
machine to stop before disabling it. I wonder if that also applies to reset?
-Mike
next prev parent reply other threads:[~2010-09-09 21:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-07 20:25 [PATCH v3 00/10] split out emac cpdma and mdio for reuse Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 01/10] net: davinci_emac: separate out davinci mdio Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 02/10] davinci: add mdio platform devices Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 03/10] omap: " Cyril Chemparathy
2010-09-08 1:00 ` Tony Lindgren
2010-09-07 20:25 ` [PATCH v3 04/10] net: davinci_emac: switch to new mdio Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 05/10] davinci: cleanup unused davinci mdio arch code Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 06/10] omap: " Cyril Chemparathy
2010-09-08 1:00 ` Tony Lindgren
2010-09-07 20:25 ` [PATCH v3 07/10] net: davinci_emac: cleanup unused mdio emac code Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 08/10] net: davinci_emac: separate out cpdma code Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 09/10] net: davinci_emac: switch to new cpdma layer Cyril Chemparathy
2010-09-07 20:25 ` [PATCH v3 10/10] net: davinci_emac: cleanup unused cpdma code Cyril Chemparathy
2010-09-08 1:18 ` [PATCH v3 00/10] split out emac cpdma and mdio for reuse Kevin Hilman
2010-09-08 2:22 ` Michael Williamson
2010-09-08 21:59 ` Cyril Chemparathy
2010-09-09 0:47 ` Michael Williamson
2010-09-09 18:43 ` Michael Williamson
2010-09-09 19:51 ` Cyril Chemparathy
2010-09-09 21:24 ` Cyril Chemparathy
2010-09-09 21:45 ` Michael Williamson [this message]
2010-09-09 21:25 ` Michael Williamson
2010-09-10 15:23 ` Caglar Akyuz
2010-09-11 8:54 ` Caglar Akyuz
2010-09-13 14:09 ` Cyril Chemparathy
2010-09-13 15:46 ` Cyril Chemparathy
2010-09-13 17:51 ` Caglar Akyuz
2010-09-10 22:59 ` Cyril Chemparathy
2010-09-11 13:14 ` Michael Williamson
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