From: Bartosz Golaszewski <brgl@bgdev.pl> To: David Lechner <david@lechnology.com> Cc: Sekhar Nori <nsekhar@ti.com>, Kevin Hilman <khilman@kernel.org>, Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, devicetree <devicetree@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Bartosz Golaszewski <bgolaszewski@baylibre.com> Subject: Re: [PATCH 0/4] ARM: da850: enable cpufreq in DT mode Date: Thu, 21 Mar 2019 16:40:02 +0100 [thread overview] Message-ID: <CAMRc=MespSLpsknVrMwYVorv0NxAsSL+U9R049Fw_Wqe1_gqkw@mail.gmail.com> (raw) In-Reply-To: <e4d51b63-bc07-c595-9d73-c4b09eb11341@lechnology.com> czw., 21 mar 2019 o 16:29 David Lechner <david@lechnology.com> napisał(a): > > On 3/21/19 9:10 AM, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > This series adds cpufreq-dt operating points for da850 boards supported > > with device tree (da850-lcdk, da850-lego-ev3, da850-evm) and also > > includes a fix for the da850-evm boardfile which checks an unset variable > > to determine the highest available frequency for cpufreq. > > > I can't find any old threads about this, but I recall that there was a > problem with the USB OHCI controller breaking when switching frequencies. > It didn't happen all of the time, but often enough that it made using > cpufreq unusable for me. Is this still a problem? > Yes, it's still a problem, but it's bug-compatible with the legacy BSP from TI (project arago). I've spent some time trying to figure out the culprit at the time you were working on the clock driver, but eventually gave up. I think it's some kind of a HW issue. The controller would simple die after a couple transitions. Bart > Also, a big-picture question. On boards with fixed regulators, what is > the benefit of enabling frequency scaling? The power savings aspect > seems negligible (< 1% in my tests) since the voltage cannot be changed.
WARNING: multiple messages have this Message-ID (diff)
From: Bartosz Golaszewski <brgl@bgdev.pl> To: David Lechner <david@lechnology.com> Cc: Mark Rutland <mark.rutland@arm.com>, devicetree <devicetree@vger.kernel.org>, Kevin Hilman <khilman@kernel.org>, Sekhar Nori <nsekhar@ti.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Bartosz Golaszewski <bgolaszewski@baylibre.com>, Rob Herring <robh+dt@kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH 0/4] ARM: da850: enable cpufreq in DT mode Date: Thu, 21 Mar 2019 16:40:02 +0100 [thread overview] Message-ID: <CAMRc=MespSLpsknVrMwYVorv0NxAsSL+U9R049Fw_Wqe1_gqkw@mail.gmail.com> (raw) In-Reply-To: <e4d51b63-bc07-c595-9d73-c4b09eb11341@lechnology.com> czw., 21 mar 2019 o 16:29 David Lechner <david@lechnology.com> napisał(a): > > On 3/21/19 9:10 AM, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > This series adds cpufreq-dt operating points for da850 boards supported > > with device tree (da850-lcdk, da850-lego-ev3, da850-evm) and also > > includes a fix for the da850-evm boardfile which checks an unset variable > > to determine the highest available frequency for cpufreq. > > > I can't find any old threads about this, but I recall that there was a > problem with the USB OHCI controller breaking when switching frequencies. > It didn't happen all of the time, but often enough that it made using > cpufreq unusable for me. Is this still a problem? > Yes, it's still a problem, but it's bug-compatible with the legacy BSP from TI (project arago). I've spent some time trying to figure out the culprit at the time you were working on the clock driver, but eventually gave up. I think it's some kind of a HW issue. The controller would simple die after a couple transitions. Bart > Also, a big-picture question. On boards with fixed regulators, what is > the benefit of enabling frequency scaling? The power savings aspect > seems negligible (< 1% in my tests) since the voltage cannot be changed. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-21 15:40 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-21 14:10 [PATCH 0/4] ARM: da850: enable cpufreq in DT mode Bartosz Golaszewski 2019-03-21 14:10 ` Bartosz Golaszewski 2019-03-21 14:10 ` [PATCH 1/4] ARM: davinci: fix cpufreq registration on da850-evm Bartosz Golaszewski 2019-03-21 14:10 ` Bartosz Golaszewski 2019-03-21 14:10 ` [PATCH 2/4] ARM: dts: da850: add cpu node and operating points to DT Bartosz Golaszewski 2019-03-21 14:10 ` Bartosz Golaszewski 2019-03-21 15:56 ` David Lechner 2019-03-21 15:56 ` David Lechner 2019-03-21 14:10 ` [PATCH 3/4] ARM: dts: da850-evm: enable cpufreq Bartosz Golaszewski 2019-03-21 14:10 ` Bartosz Golaszewski 2019-03-21 15:53 ` David Lechner 2019-03-21 15:53 ` David Lechner 2019-03-21 16:36 ` Bartosz Golaszewski 2019-03-21 16:36 ` Bartosz Golaszewski 2019-03-21 16:43 ` Bartosz Golaszewski 2019-03-21 16:43 ` Bartosz Golaszewski 2019-03-21 17:13 ` Bartosz Golaszewski 2019-03-21 17:13 ` Bartosz Golaszewski 2019-03-21 14:10 ` [PATCH 4/4] ARM: davinci_all_defconfig: Enable CPUFREQ_DT Bartosz Golaszewski 2019-03-21 14:10 ` Bartosz Golaszewski 2019-03-21 15:29 ` [PATCH 0/4] ARM: da850: enable cpufreq in DT mode David Lechner 2019-03-21 15:29 ` David Lechner 2019-03-21 15:40 ` Bartosz Golaszewski [this message] 2019-03-21 15:40 ` Bartosz Golaszewski
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