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Wed, 30 Jun 2021 19:05:53 -0700 (PDT) Date: Thu, 1 Jul 2021 07:35:51 +0530 From: Viresh Kumar To: Marek =?utf-8?B?QmVow7pu?= Cc: Gregory CLEMENT , Ken Ma , Victor Gu , Robert Marko , Pali =?utf-8?B?Um9ow6Fy?= , Tomasz Maciej Nowak , Anders Trier Olesen , Philip Soares , linux-pm@vger.kernel.org, Sebastian Hesselbarth , linux-arm-kernel@lists.infradead.org, Konstantin Porotchkin , nnet , Nadav Haklai Subject: Re: [PATCH v2] cpufreq: armada-37xx: forbid cpufreq for 1.2 GHz variant Message-ID: <20210701020551.svhbjpbdw526cq7a@vireshk-i7> References: <20210630135942.29730-1-kabel@kernel.org> <20210630225601.6372-1-kabel@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210630225601.6372-1-kabel@kernel.org> User-Agent: NeoMutt/20180716-391-311a52 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210630_190558_157676_63B6F0D5 X-CRM114-Status: GOOD ( 25.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 01-07-21, 00:56, Marek Beh=FAn 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 Beh=FAn > 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/d6719fd= c2b3cac58064f41b531f86993c919aa9a > 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(-) I am not picking it up for 5.14-rc1 to make sure others get a chance to provide reviews. -- = viresh _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel