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[71.197.186.152]) by smtp.googlemail.com with ESMTPSA id z62sm4484115pfl.33.2018.11.29.15.28.43 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 29 Nov 2018 15:28:44 -0800 (PST) From: Kevin Hilman To: Martin Blumenstingl Cc: linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux@armlinux.org.uk Subject: Re: [PATCH] ARM: multi_v7_defconfig: switch CONFIG_PWM_MESON to built-in In-Reply-To: References: <20181114230554.4968-1-martin.blumenstingl@googlemail.com> <7hh8g0d8tg.fsf@baylibre.com> Date: Thu, 29 Nov 2018 15:28:42 -0800 Message-ID: <7hk1kv79at.fsf@baylibre.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Martin Blumenstingl writes: > Hi Kevin, > > On Thu, Nov 29, 2018 at 1:30 AM Kevin Hilman wrote: >> >> Martin Blumenstingl writes: >> >> > Some Meson8b boards (Odroid-C1, EC-100) use a PWM regulator which is the >> > voltage supply of the CPU cores (this regulator is typically called >> > "VCCK"). >> > Now that we are preparing support for CPU frequency scaling on Meson8, >> > Meson8b and Meson8m2 we should build the pwm-meson driver into the >> > kernel so we can configure the CPU voltage early in the boot process. >> >> Can you explain a little more why the configuration of CPU voltage >> cannot wait a bit so this could be properly probed? > > I was under the impression that cpufreq-dt would still initialize even > if the regulator is not ready yet. however (after reading the code > again) this is clearly NOT the case. Hmm, a quick look at cpufreq-dt suggests that it should -EPROBE_DEFER if the regulator isn't ready yet. Why doesn't that work? > there's still a benefit with this change: your Odroid-C1 in your > KernelCI lab would also be able to change the CPU frequency (so in > case something breaks we could spot it there). > will you accept this patch after I updated the description to mention > that it's for KernelCI test coverage? Possibly, but I'd still rather see the dependencies worked out correctly so that this can be module, and cpufreq-dt would defer until it's ready. Kevin