linux-kernel - Re: [PATCH v3 1/3] ARM: dts: da850: add cpu node and operating points to DT

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Date:   Fri, 12 Apr 2019 17:31:12 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Sekhar Nori <nsekhar@...com>
Cc:     Kevin Hilman <khilman@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Lechner <david@...hnology.com>,
        Adam Ford <aford173@...il.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH v3 1/3] ARM: dts: da850: add cpu node and operating points
 to DT

pt., 12 kwi 2019 o 15:53 Sekhar Nori <nsekhar@...com> napisał(a):
>
> On 12/04/19 5:41 PM, Bartosz Golaszewski wrote:
> > pt., 12 kwi 2019 o 13:26 Sekhar Nori <nsekhar@...com> napisał(a):
> >>
> >> Hi Bartosz,
> >>
> >> On 08/04/19 1:29 PM, Bartosz Golaszewski wrote:
> >>> From: David Lechner <david@...hnology.com>
> >>>
> >>> This adds a cpu node and operating points to the common da850.dtsi file.
> >>>
> >>> Additionally, a regulator is added to the LEGO EV3 board along with
> >>> some board-specific CPU configuration.
> >>>
> >>> Regulators need to be hooked up on other boards to get them working.
> >>>
> >>> Signed-off-by: David Lechner <david@...hnology.com>
> >>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >>
> >> I remember you mentioning about some problems using OCHI and cpufreq
> >> together. Are those resolved now? CPU PLL on DA850 can affect other
> >> peripheral clock frequencies too. So enabling it should really be a
> >> per-board decision.
> >>
> >
> > The problems are still there. I've never been able to find the
> > culprit, but it also occurs on TI BSP in the same way (a couple
> > cpufreq transitions will make the controller unresponsive).
>
> Is that on LCDK as well? As I recall cpufreq was never enabled on LCDK
> in TI BSP.
>

Yes, I just verified that the bug occurs on LCDK with patches from this series.

> If the OHCI problem is present on LCDK, then there is a user visible
> regression on mainline after this patch. Lets enable cpufreq in LCDK
> only if all working peripherals keep working afterwards.
>

The OHCI driver doesn't register any cpufreq transition notifier
callbacks. I can't really find anything in the datasheet, but I'm
wondering if we shouldn't do something similar to what the driver for
davinci i2c controller does. I'll try a couple things tomorrow.

Bart