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From: "Pali Rohár" <pali@kernel.org>
To: Konstantin Porotchkin <kostap@marvell.com>,
	Nadav Haklai <nadavh@marvell.com>, Ken Ma <make@marvell.com>,
	Victor Gu <xigu@marvell.com>,
	Jason Hung <jhung@globalscaletechnologies.com>
Cc: "Marek Behún" <kabel@kernel.org>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Gregory CLEMENT" <gregory.clement@bootlin.com>,
	"Robert Marko" <robert.marko@sartura.hr>,
	"Tomasz Maciej Nowak" <tmn505@gmail.com>,
	"Anders Trier Olesen" <anders.trier.olesen@gmail.com>,
	"Philip Soares" <philips@netisense.com>,
	linux-pm@vger.kernel.org,
	"Sebastian Hesselbarth" <sebastian.hesselbarth@gmail.com>,
	linux-arm-kernel@lists.infradead.org, nnet <nnet@fastmail.fm>
Subject: Re: [PATCH v2] cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant
Date: Thu, 8 Jul 2021 16:34:51 +0200	[thread overview]
Message-ID: <20210708143451.4htvdop4zvjufrq6@pali> (raw)
In-Reply-To: <20210702163035.nmb5pniwpqtmaz4b@pali>

Konstantin, Nadav, Ken, Victor, Jason: This issue is pretty serious,
CPU on 1.2GHz A3720 is crashing. Could you please look at it?

On Friday 02 July 2021 18:30:35 Pali Rohár wrote:
> +Jason from GlobalScale as this issue affects GlobalScale Espressobin Ultra and V7 1.2 GHz boards.
> 
> On Thursday 01 July 2021 00:56:01 Marek Behún wrote:
> > The 1.2 GHz variant of the Armada 3720 SOC is unstable with DVFS: when
> > the SOC boots, the WTMI firmware sets clocks and AVS values that work
> > correctly with 1.2 GHz CPU frequency, but random crashes occur once
> > cpufreq driver starts scaling.
> > 
> > We do not know currently what is the reason:
> > - it may be that the voltage value for L0 for 1.2 GHz variant provided
> >   by the vendor in the OTP is simply incorrect when scaling is used,
> > - it may be that some delay is needed somewhere,
> > - it may be something else.
> > 
> > The most sane solution now seems to be to simply forbid the cpufreq
> > driver on 1.2 GHz variant.
> > 
> > Signed-off-by: Marek Behún <kabel@kernel.org>
> > Fixes: 92ce45fb875d ("cpufreq: Add DVFS support for Armada 37xx")
> > ---
> > If someone from Marvell could look into this, it would be great since
> > basically 1.2 GHz variant cannot scale, which is a feature that was
> > claimed to be supported by the SOC.
> > 
> > Ken Ma / Victor Gu, you have worked on commit
> > https://github.com/MarvellEmbeddedProcessors/linux-marvell/commit/d6719fdc2b3cac58064f41b531f86993c919aa9a
> > in linux-marvell.
> > Your patch takes away the 1202 mV constant for 1.2 GHz base CPU
> > frequency and instead adds code that computes the voltages from the
> > voltage found in L0 AVS register (which is filled in by WTMI firmware).
> > 
> > Do you know why the code does not work correctly for some 1.2 GHz
> > boards? Do we need to force the L0 voltage to 1202 mV if it is lower,
> > or something?
> > ---
> >  drivers/cpufreq/armada-37xx-cpufreq.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
> > index 3fc98a3ffd91..c10fc33b29b1 100644
> > --- a/drivers/cpufreq/armada-37xx-cpufreq.c
> > +++ b/drivers/cpufreq/armada-37xx-cpufreq.c
> > @@ -104,7 +104,11 @@ struct armada_37xx_dvfs {
> >  };
> >  
> >  static struct armada_37xx_dvfs armada_37xx_dvfs[] = {
> > -	{.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} },
> > +	/*
> > +	 * The cpufreq scaling for 1.2 GHz variant of the SOC is currently
> > +	 * unstable because we do not know how to configure it properly.
> > +	 */
> > +	/* {.cpu_freq_max = 1200*1000*1000, .divider = {1, 2, 4, 6} }, */
> >  	{.cpu_freq_max = 1000*1000*1000, .divider = {1, 2, 4, 5} },
> >  	{.cpu_freq_max = 800*1000*1000,  .divider = {1, 2, 3, 4} },
> >  	{.cpu_freq_max = 600*1000*1000,  .divider = {2, 4, 5, 6} },
> > -- 
> > 2.31.1
> > 

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  reply	other threads:[~2021-07-08 14:36 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-30 13:59 [PATCH] " Marek Behún
2021-06-30 14:02 ` Marek Behún
2021-06-30 15:22 ` Andrew Lunn
2021-06-30 22:56 ` [PATCH v2] " Marek Behún
2021-07-01  2:05   ` Viresh Kumar
2021-07-02 16:30   ` Pali Rohár
2021-07-08 14:34     ` Pali Rohár [this message]
2021-07-15 19:33       ` Pali Rohár
2021-08-08 19:30         ` Pali Rohár
2021-08-09  4:02           ` Viresh Kumar
2022-08-01 12:36           ` Pali Rohár
2022-08-01 14:01             ` [EXT] " Elad Nachman
2022-08-01 14:12               ` Pali Rohár
2022-08-01 14:15                 ` Elad Nachman
2022-08-01 17:56                   ` Pali Rohár
     [not found]                     ` <BN9PR18MB42518C761E574D862D30CDA7DB9A9@BN9PR18MB4251.namprd18.prod.outlook.com>
2022-08-02 16:42                       ` Robert Marko
2022-08-02 16:52                         ` Elad Nachman
2022-08-02 16:56                           ` Robert Marko
2022-08-02 17:17                             ` Pali Rohár
2022-08-17  9:40                               ` Robert Marko
2022-08-17 23:10                                 ` Pali Rohár
2022-08-18  8:14                                   ` Robert Marko
2022-08-25 21:49                                     ` Pali Rohár

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