Messages in this thread | | | Subject | Re: [RFC v2 3/5] clk: bcm2835: use firmware interface to update pllb | From | Stefan Wahren <> | Date | Tue, 21 May 2019 14:40:58 +0200 |
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Hi Nicolas,
On 20.05.19 14:11, Stefan Wahren wrote: > Hi Nicolas, > > the following comments applies only in case Eric is fine with the whole > approach. > > On 20.05.19 12:47, Nicolas Saenz Julienne wrote: >> Raspberry Pi's firmware, which runs in a dedicated processor, keeps > maybe we should clarify that the firmware is running in the VPU >> track of the board's temperature and voltage. It's resposible for >> scaling the CPU frequency whenever it deems the device reached an unsafe >> state. On top of that the firmware provides an interface which allows >> Linux to to query the clock's state or change it's frequency. > I think this requires a separate update of the devicetree binding. >> Being the sole user of the bcm2835 clock driver, this integrates the >> firmware interface into the clock driver and adds a first user: the CPU >> pll, also known as 'pllb'. > Please verify that the kernel still works (and this clock driver probe) > under the following conditions: > > - CONFIG_RASPBERRYPI_FIRMWARE=n > - CONFIG_RASPBERRYPI_FIRMWARE=m > - older DTBs without patch #1 i thought about this and the case this driver would return -EPROBE_DEFER. The clock driver is too essential for doing such a thing. So i think the best solution would be to move these changes into a separate driver which should be register by the clock driver (similiar to vchiq). This also avoid the need of a new device tree binding.
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