Re: [beagleboard] Re: USB EHCI problems

Re: [beagleboard] Re: USB EHCI problems

[Siarhei Siamashka]

On Saturday 15 August 2009, Frantisek Dufka wrote:
> Gerald Coley wrote:
> > You need to enable Smart Reflex on VDD2 in the Kernel. I can't seem to
> > get anyone around here to help me formalize exactly how to do this in
> > the Kernel. So if you can figure it out, I would go ahead and do it. If
> > you could please then post it to the community, that would be great.
> >
> > Gerald
>
> http://www.webos-internals.org/wiki/Patch_webOS_CPU_Frequency_or_Voltage_Sc
>aling#Enable_SmartReflex
>
> the file is there but after running
> echo -n 1 > /sys/power/sr_vdd2_autocomp
> there is still zero in the file and in kernel log I see
> OPP3 doesn't support SmartReflex
> SR2: VDD autocomp not activated
>
> Maybe different kernel would do.

Would it make sense to ask for help in the linux-omap mailing list?
I guess Gerald has a reply from TI or a new errata list or something else
which says that "enabling Smart Reflex on VDD2" can workaround EHCI problem.

Now somebody knowledgeable about kernel internals, OMAP3, Smart Reflex
and power management code in general could probably provide some hints
or even a patch to enable this bugfix in the kernel. Maybe the fix is even
sitting in somebody's branch already and we just don't know. Or maybe a
solution for EHCI problem has been explained in the list, but just was
lost in the pile of other messages in linux-omap (it has quite a heavy
traffic).

It may make sense to look at the 'pm' branch:
http://elinux.org/OMAP_Power_Management

But this wiki page has comment:
"Enables SmartReflex autocompensation on VDD2 (Note: This feature can only be 
tested on a ES3.1 silicon):
# echo 1 > /sys/power/sr_vdd2_autocomp"

And AFAIK beagleboard revision C has ES3.0 silicon. So no luck here. Or can
something still be done?

The whole beagleboard EHCI story starts here:
http://groups.google.com/group/beagleboard/browse_thread/thread/5b8385f0bb1f63da/d46625fe49783a8a

-- 
Best regards,
Siarhei Siamashka

Re: [beagleboard] Re: USB EHCI problems

[Gregoire Gentil]

On the Touch Book (which has the same transceiver as Beagleboard), we
experience a similar problem with high speed USB. I'm playing with those
various options and patches but it's not working so far. I'm then very
interested to get any help on this problem too. More documentation about
Smart Reflex would help,

Grégoire


On Sat, 2009-08-15 at 23:04 +0300, Siarhei Siamashka wrote:
> On Saturday 15 August 2009, Frantisek Dufka wrote:
> > Gerald Coley wrote:
> > > You need to enable Smart Reflex on VDD2 in the Kernel. I can't seem to
> > > get anyone around here to help me formalize exactly how to do this in
> > > the Kernel. So if you can figure it out, I would go ahead and do it. If
> > > you could please then post it to the community, that would be great.
> > >
> > > Gerald
> >
> > http://www.webos-internals.org/wiki/Patch_webOS_CPU_Frequency_or_Voltage_Sc
> >aling#Enable_SmartReflex
> >
> > the file is there but after running
> > echo -n 1 > /sys/power/sr_vdd2_autocomp
> > there is still zero in the file and in kernel log I see
> > OPP3 doesn't support SmartReflex
> > SR2: VDD autocomp not activated
> >
> > Maybe different kernel would do.
> 
> Would it make sense to ask for help in the linux-omap mailing list?
> I guess Gerald has a reply from TI or a new errata list or something else
> which says that "enabling Smart Reflex on VDD2" can workaround EHCI problem.
> 
> Now somebody knowledgeable about kernel internals, OMAP3, Smart Reflex
> and power management code in general could probably provide some hints
> or even a patch to enable this bugfix in the kernel. Maybe the fix is even
> sitting in somebody's branch already and we just don't know. Or maybe a
> solution for EHCI problem has been explained in the list, but just was
> lost in the pile of other messages in linux-omap (it has quite a heavy
> traffic).
> 
> It may make sense to look at the 'pm' branch:
> http://elinux.org/OMAP_Power_Management
> 
> But this wiki page has comment:
> "Enables SmartReflex autocompensation on VDD2 (Note: This feature can only be 
> tested on a ES3.1 silicon):
> # echo 1 > /sys/power/sr_vdd2_autocomp"
> 
> And AFAIK beagleboard revision C has ES3.0 silicon. So no luck here. Or can
> something still be done?
> 
> The whole beagleboard EHCI story starts here:
> http://groups.google.com/group/beagleboard/browse_thread/thread/5b8385f0bb1f63da/d46625fe49783a8a
> 

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Re: [beagleboard] Re: USB EHCI problems

[Paul Walmsley]

Hi

On Sat, 15 Aug 2009, Siarhei Siamashka wrote:

> But this wiki page has comment:
> "Enables SmartReflex autocompensation on VDD2 (Note: This feature can only be 
> tested on a ES3.1 silicon):
> # echo 1 > /sys/power/sr_vdd2_autocomp"
> 
> And AFAIK beagleboard revision C has ES3.0 silicon. So no luck here. Or can
> something still be done?

It should be possible to enable SmartReflex on <ES3.1, but the SR register 
values need to be programmed at runtime.  (ES3.1 has the SR register 
values blown in to eFUSE OTPROM)

As far as I know, only TI has this information, so it's up to them to 
release it.  Although one of the device vendor kernel patches/tarballs 
might have something useful here - I haven't looked recently.


- Paul

RE: [beagleboard] Re: USB EHCI problems

[Woodruff, Richard]

> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
> owner@vger.kernel.org] On Behalf Of Siarhei Siamashka
> Sent: Saturday, August 15, 2009 3:04 PM

> On Saturday 15 August 2009, Frantisek Dufka wrote:
> > Gerald Coley wrote:
> > > You need to enable Smart Reflex on VDD2 in the Kernel. I can't seem to
> > > get anyone around here to help me formalize exactly how to do this in
> > > the Kernel. So if you can figure it out, I would go ahead and do it. If
> > > you could please then post it to the community, that would be great.
> > >
> > > Gerald
> >
> > http://www.webos-internals.org/wiki/Patch_webOS_CPU_Frequency_or_Voltage_Sc
> >aling#Enable_SmartReflex

Seems hacking moves along fast, some basic info and mis-info on Pre.  Pre kernel which is shipped needs a few patches and it is capable of running sr+dvfs at the same time.

> > the file is there but after running
> > echo -n 1 > /sys/power/sr_vdd2_autocomp
> > there is still zero in the file and in kernel log I see
> > OPP3 doesn't support SmartReflex
> > SR2: VDD autocomp not activated

In older code you need both compile time and run time to get it to take.  Just turning it on won't be so safe until some bug fixes make their way out.

> It may make sense to look at the 'pm' branch:
> http://elinux.org/OMAP_Power_Management

pm branch needs a few changes to make it viable for sr.

> But this wiki page has comment:
> "Enables SmartReflex autocompensation on VDD2 (Note: This feature can only be
> tested on a ES3.1 silicon):
> # echo 1 > /sys/power/sr_vdd2_autocomp"
>
> And AFAIK beagleboard revision C has ES3.0 silicon. So no luck here. Or can
> something still be done?

You will only find characterized parameters for 3.1 and 3.1.1.  These are production parts.

I had heard a few bits of talk about running at lower voltage helping ehci out.  That seems backwards even if tests show it working. I wonder if it is some artifact of a timing change which happens at lower voltage and because of some new internal chip activity.

Regards,
Richard W.