linux-kernel - Re: [PATCH v5 4/5] ARM: dts: da850-evm: enable cpufreq

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Date:   Fri, 24 May 2019 18:58:04 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Adam Ford <aford173@...il.com>, Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        David Lechner <david@...hnology.com>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 4/5] ARM: dts: da850-evm: enable cpufreq

wt., 23 kwi 2019 o 11:15 Bartosz Golaszewski
<bgolaszewski@...libre.com> napisał(a):
>
> śr., 17 kwi 2019 o 19:09 Adam Ford <aford173@...il.com> napisał(a):
> >
> > On Wed, Apr 17, 2019 at 10:27 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> > >
> > > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> > >
> > > Enable cpufreq-dt support for da850-evm. The cvdd is supplied by the
> > > tps65070 pmic with configurable output voltage. By default da850-evm
> > > boards support frequencies up to 375MHz so enable this operating
> > > point.
> >
> > Have you done any testing with the LCD on any of the devices you have?
> >
> > I enabled the ondemand governor, and I got a bunch of splat from the
> > LCD controller:
> >
> > tilcdc 1e13000.display: effective pixel clock rate (50000000Hz)
> > differs from the calculated rate (54000000Hz)
> > tilcdc 1e13000.display: tilcdc_crtc_irq(0x00000161): FIFO underflow
> > tilcdc 1e13000.display: tilcdc_crtc_irq(0x00000161): FIFO underflow
> > ... [ snip]
> > tilcdc 1e13000.display: effective pixel clock rate (50000000Hz)
> > differs from the calculated rate (54000000Hz)
> > tilcdc 1e13000.display: effective pixel clock rate (50000000Hz)
> > differs from the calculated rate (54000000Hz)
> > tilcdc 1e13000.display: tilcdc_crtc_irq(0x00000161): FIFO underflow
> >
> > It appears to go on forever.  I don't necessarily want to hold it up,
> > but I don't know the clocking system well enough to know where to go
> > investigate it.  I can certainly live without ondemand.  Using
> > userspace as the default governor is fine for me for now.
> >
> > adam
>
> Hi Adam,
>
> I did test the tilcdc on da850-lcdk. The only message I'm getting
> during transitions is a single:
>
> tilcdc <name>: tilcdc_crtc_irq(<address>): FIFO underflow
>
> but this is fairly normal - we also get this during modeset and it
> doesn't affect the display.
>
> The problem with the pixel clock may come from the bootloader - are
> you using a recent version of u-boot?
>
> Bart
>
> > >
> > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> > > Reviewed-by: Adam Ford <aford173@...il.com>
> > > ---
> > >  arch/arm/boot/dts/da850-evm.dts | 13 +++++++++++++
> > >  1 file changed, 13 insertions(+)
> > >
> > > diff --git a/arch/arm/boot/dts/da850-evm.dts b/arch/arm/boot/dts/da850-evm.dts
> > > index f04bc3e15332..f94bb38fdad9 100644
> > > --- a/arch/arm/boot/dts/da850-evm.dts
> > > +++ b/arch/arm/boot/dts/da850-evm.dts
> > > @@ -191,6 +191,19 @@
> > >         };
> > >  };
> > >
> > > +&cpu {
> > > +       cpu-supply = <&vdcdc3_reg>;
> > > +};
> > > +
> > > +/*
> > > + * The standard da850-evm kits and SOM's are 375MHz so enable this operating
> > > + * point by default. Higher frequencies must be enabled for custom boards with
> > > + * other variants of the SoC.
> > > + */
> > > +&opp_375 {
> > > +       status = "okay";
> > > +};
> > > +
> > >  &sata {
> > >         status = "okay";
> > >  };
> > > --
> > > 2.21.0
> > >

Hi Adam,

did you figure out the problem by chance? Are you OK with merging this series?

Bart