From: Tony Lindgren <tony@atomide.com>
To: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: vinod.koul@intel.com, nsekhar@ti.com,
linux-kernel@vger.kernel.org, t-kristo@ti.com,
dmaengine@vger.kernel.org, dan.j.williams@intel.com,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] dmaengine: edma: Remove dynamic TPTC power management feature
Date: Thu, 28 Jan 2016 09:11:46 -0800 [thread overview]
Message-ID: <20160128171146.GC19432@atomide.com> (raw)
In-Reply-To: <56A9D8C2.7000401@ti.com>
* Peter Ujfalusi <peter.ujfalusi@ti.com> [160128 01:01]:
> On 01/27/2016 05:54 PM, Tony Lindgren wrote:
> > * Peter Ujfalusi <peter.ujfalusi@ti.com> [160127 01:12]:
> >> The dynamic or on demand pm_runtime does not work correctly on am335x and
> >> am437x due to interference with hwmod.
> >
> > Hmm care expand a bit what is the problem with this "interference"?
>
> The idea was to enable/power on only the TPTCs which is actually in use and
> leave the unused ones off. Which is is nice and all, but...
> The original implementation did the pm_runtime calls for the tptcs from the
> edma tpcc driver instance and the main issue was that I did the pm_runtime
> calls in the edma-tpcc pm callbacks as well.
> Since omap hwmod/device also handles pm_runtime on behalf of the drivers we
> got nasty issues, kernel crash, warnings on suspend/resume.
>
> Then I did implemented the on demand power management in a totally different
> way, still keeping only tptcs enabled which is in use.
> In this way all the omap hwmod/device incoherency was gone and things looked
> fine, but it turned out that on second suspend we are not able to wake up the
> board.
> I and Tero debugged this a bit and it turns out that we need to kepp all tptcs
> enabled and powered, otherwise the HW will not going to be able to complete
> the transition, breaking suspend/resume.
Probably you only need to keep the tptcs being used enabled though? They
should be completely independent otherwise?
> With pm_runtime_enable() + get_sync() on all tptcs we can suspend and resume
> w/o problems and they will be disabled/enabled by omap hwmod/device code,
> following nicely the power state of the system.
>
> As a note: I did tried the suspend/resume with the old code with dra7, but it
> turned out that on dra7 SW has no control over the tptc power state, it
> follows the system in HW.
>
> In short: The implementation was flawed and even if the implementation is
> correct the HW will lock up if we do on demand tptc power management.
OK interesting.
Regards,
Tony
WARNING: multiple messages have this Message-ID (diff)
From: tony@atomide.com (Tony Lindgren)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] dmaengine: edma: Remove dynamic TPTC power management feature
Date: Thu, 28 Jan 2016 09:11:46 -0800 [thread overview]
Message-ID: <20160128171146.GC19432@atomide.com> (raw)
In-Reply-To: <56A9D8C2.7000401@ti.com>
* Peter Ujfalusi <peter.ujfalusi@ti.com> [160128 01:01]:
> On 01/27/2016 05:54 PM, Tony Lindgren wrote:
> > * Peter Ujfalusi <peter.ujfalusi@ti.com> [160127 01:12]:
> >> The dynamic or on demand pm_runtime does not work correctly on am335x and
> >> am437x due to interference with hwmod.
> >
> > Hmm care expand a bit what is the problem with this "interference"?
>
> The idea was to enable/power on only the TPTCs which is actually in use and
> leave the unused ones off. Which is is nice and all, but...
> The original implementation did the pm_runtime calls for the tptcs from the
> edma tpcc driver instance and the main issue was that I did the pm_runtime
> calls in the edma-tpcc pm callbacks as well.
> Since omap hwmod/device also handles pm_runtime on behalf of the drivers we
> got nasty issues, kernel crash, warnings on suspend/resume.
>
> Then I did implemented the on demand power management in a totally different
> way, still keeping only tptcs enabled which is in use.
> In this way all the omap hwmod/device incoherency was gone and things looked
> fine, but it turned out that on second suspend we are not able to wake up the
> board.
> I and Tero debugged this a bit and it turns out that we need to kepp all tptcs
> enabled and powered, otherwise the HW will not going to be able to complete
> the transition, breaking suspend/resume.
Probably you only need to keep the tptcs being used enabled though? They
should be completely independent otherwise?
> With pm_runtime_enable() + get_sync() on all tptcs we can suspend and resume
> w/o problems and they will be disabled/enabled by omap hwmod/device code,
> following nicely the power state of the system.
>
> As a note: I did tried the suspend/resume with the old code with dra7, but it
> turned out that on dra7 SW has no control over the tptc power state, it
> follows the system in HW.
>
> In short: The implementation was flawed and even if the implementation is
> correct the HW will lock up if we do on demand tptc power management.
OK interesting.
Regards,
Tony
WARNING: multiple messages have this Message-ID (diff)
From: Tony Lindgren <tony@atomide.com>
To: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: vinod.koul@intel.com, dan.j.williams@intel.com,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
nsekhar@ti.com, t-kristo@ti.com
Subject: Re: [PATCH] dmaengine: edma: Remove dynamic TPTC power management feature
Date: Thu, 28 Jan 2016 09:11:46 -0800 [thread overview]
Message-ID: <20160128171146.GC19432@atomide.com> (raw)
In-Reply-To: <56A9D8C2.7000401@ti.com>
* Peter Ujfalusi <peter.ujfalusi@ti.com> [160128 01:01]:
> On 01/27/2016 05:54 PM, Tony Lindgren wrote:
> > * Peter Ujfalusi <peter.ujfalusi@ti.com> [160127 01:12]:
> >> The dynamic or on demand pm_runtime does not work correctly on am335x and
> >> am437x due to interference with hwmod.
> >
> > Hmm care expand a bit what is the problem with this "interference"?
>
> The idea was to enable/power on only the TPTCs which is actually in use and
> leave the unused ones off. Which is is nice and all, but...
> The original implementation did the pm_runtime calls for the tptcs from the
> edma tpcc driver instance and the main issue was that I did the pm_runtime
> calls in the edma-tpcc pm callbacks as well.
> Since omap hwmod/device also handles pm_runtime on behalf of the drivers we
> got nasty issues, kernel crash, warnings on suspend/resume.
>
> Then I did implemented the on demand power management in a totally different
> way, still keeping only tptcs enabled which is in use.
> In this way all the omap hwmod/device incoherency was gone and things looked
> fine, but it turned out that on second suspend we are not able to wake up the
> board.
> I and Tero debugged this a bit and it turns out that we need to kepp all tptcs
> enabled and powered, otherwise the HW will not going to be able to complete
> the transition, breaking suspend/resume.
Probably you only need to keep the tptcs being used enabled though? They
should be completely independent otherwise?
> With pm_runtime_enable() + get_sync() on all tptcs we can suspend and resume
> w/o problems and they will be disabled/enabled by omap hwmod/device code,
> following nicely the power state of the system.
>
> As a note: I did tried the suspend/resume with the old code with dra7, but it
> turned out that on dra7 SW has no control over the tptc power state, it
> follows the system in HW.
>
> In short: The implementation was flawed and even if the implementation is
> correct the HW will lock up if we do on demand tptc power management.
OK interesting.
Regards,
Tony
next prev parent reply other threads:[~2016-01-28 17:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-27 9:11 [PATCH] dmaengine: edma: Remove dynamic TPTC power management feature Peter Ujfalusi
2016-01-27 9:11 ` Peter Ujfalusi
2016-01-27 9:11 ` Peter Ujfalusi
2016-01-27 15:54 ` Tony Lindgren
2016-01-27 15:54 ` Tony Lindgren
2016-01-28 9:00 ` Peter Ujfalusi
2016-01-28 9:00 ` Peter Ujfalusi
2016-01-28 9:00 ` Peter Ujfalusi
2016-01-28 17:11 ` Tony Lindgren [this message]
2016-01-28 17:11 ` Tony Lindgren
2016-01-28 17:11 ` Tony Lindgren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160128171146.GC19432@atomide.com \
--to=tony@atomide.com \
--cc=dan.j.williams@intel.com \
--cc=dmaengine@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=nsekhar@ti.com \
--cc=peter.ujfalusi@ti.com \
--cc=t-kristo@ti.com \
--cc=vinod.koul@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.