From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Riesch Subject: Re: davinci_emac/mdio: SOFT_RESET of EMAC module resets MDIO on AM1808 Date: Mon, 12 Mar 2012 08:04:52 +0100 Message-ID: References: <1330092923-10899-1-git-send-email-christian.riesch@omicron.at> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0181050159==" Cc: "netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org" , "Gole, Anant" To: "Rajashekhara, Sudhakar" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: Errors-To: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org List-Id: netdev.vger.kernel.org --===============0181050159== Content-Type: multipart/alternative; boundary="20cf303f6a26deff0204bb065b1c" --20cf303f6a26deff0204bb065b1c Content-Type: text/plain; charset="UTF-8" On Tuesday, February 28, 2012, Rajashekhara, Sudhakar wrote: > Hi Christian, > > On Mon, Feb 27, 2012 at 15:44:54, Rajashekhara, Sudhakar wrote: >> Hi Christian, >> >> On Fri, Feb 24, 2012 at 19:45:23, Christian Riesch wrote: >> > Hello Sudhakar, >> > >> > On Fri, Feb 24, 2012 at 2:02 PM, Rajashekhara, Sudhakar < sudhakar.raj-l0cyMroinI0@public.gmane.org> wrote: >> > > On Thu, Feb 23, 2012 at 14:39:49, Christian Riesch wrote: >> > >> Hi, >> > >> I observed this behavior on a Texas Instruments AM1808 SoC (AM1808 >> > >> experimenter's kit) running the current mainline kernel: >> > >> >> >> [snip] >> >> > >> >> > >> According to the AM1808 Technical Reference Manual (sections 18.2.14.1 >> > >> and 18.3.3.34 in [1]), writing a 1 to the EMAC_SOFTRESET register >> > >> resets the EMAC module, but not the MDIO module. However, when I >> > >> comment out the code above, the MDIO control register is not affected >> > >> and the warning 'resetting idled controller' disappears. >> > >> >> > > >> > > But this was not the case for me. Even after commenting out the above lines, >> > > I could still see that MDIO was getting reset. >> > >> > Uh, I am sorry. I forgot to mention that there is a second >> > emac_write(EMAC_SOFTRESET,1); in emac_dev_stop() in davinci_emac.c. >> > This one must also be commented out to make the resetting idled controller >> > message go away. >> > >> > The patch below shows that changes that I did. May I please ask you to try >> > again with these changes? >> > >> >> I was able to reproduce the issue. I'll debug this further and get back to you. >> > > I was going through the mailing list discussions where a work around for emac > soft-reset tie-up to mdio controller has been proposed. I think this was a known > issue on TI's da8xx family of devices. Please refer to the thread at > http://www.spinics.net/lists/netdev/msg140465.html. > > Cyril, > As you have mentioned in your patch, did you get any confirmation from TI designer > regarding emac soft reset behavior? I see that nothing has been mentioned in the > EMAC user guide. Ping? Thanks, Christian --20cf303f6a26deff0204bb065b1c Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

On Tuesday, February 28, 2012, Rajashekhara, Sudhakar <sudhakar.raj-l0cyMroinI0@public.gmane.org> wrote:
> = Hi Christian,
>
> On Mon, Feb 27, 2012 at 15:44:54, Rajashekhar= a, Sudhakar wrote:
>> Hi Christian,
>>
>> On Fri, Feb 24, 2012 at 19:4= 5:23, Christian Riesch wrote:
>> > Hello Sudhakar,
>> = >
>> > On Fri, Feb 24, 2012 at 2:02 PM, Rajashekhara, Sudhak= ar <sudhakar.raj-l0cyMroinI0@public.gmane.org> w= rote:
>> > > On Thu, Feb 23, 2012 at 14:39:49, Christian Riesch wrote= :
>> > >> Hi,
>> > >> I observed this b= ehavior on a Texas Instruments AM1808 SoC (AM1808
>> > >>= experimenter's kit) running the current mainline kernel:
>> > >>
>>
>> [snip]
>>
>&g= t; > >>
>> > >> According to the AM1808 Technica= l Reference Manual (sections 18.2.14.1
>> > >> and 18.3.3= .34 in [1]), writing a 1 to the EMAC_SOFTRESET register
>> > >> resets the EMAC module, but not the MDIO module. How= ever, when I
>> > >> comment out the code above, the MDIO= control register is not affected
>> > >> and the warning= 'resetting idled controller' disappears.
>> > >>
>> > >
>> > > But this= was not the case for me. Even after commenting out the above lines,
>= ;> > > I could still see that MDIO was getting reset.
>> = >
>> > Uh, I am sorry. I forgot to mention that there is a second>> > emac_write(EMAC_SOFTRESET,1); in emac_dev_stop() in davinci_= emac.c.
>> > This one must also be commented out to make the re= setting idled controller
>> > message go away.
>> >
>> > The patch = below shows that changes that I did. May I please ask you to try
>>= ; > again with these changes?
>> >
>>
>> I= was able to reproduce the issue. I'll debug this further and get back = to you.
>>
>
> I was going through the mailing list discussions w= here a work around for emac
> soft-reset tie-up to mdio controller ha= s been proposed. I think this was a known
> issue on TI's da8xx f= amily of devices. Please refer to the thread at
> http://= www.spinics.net/lists/netdev/msg140465.html.
>
> Cyril,
= > As you have mentioned in your patch, did you get any confirmation from= TI designer
> regarding emac soft reset behavior? I see that nothing has been mentio= ned in the
> EMAC user guide.

Ping?

Thanks, Christian --20cf303f6a26deff0204bb065b1c-- --===============0181050159== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============0181050159==--