On Wed, Aug 20, 2014 at 02:16:49PM -0600, Stephen Warren wrote: > On 08/13/2014 06:41 AM, Mikko Perttunen wrote: > >Hardware-triggered thermal reset requires configuring the I2C > >reset procedure. This configuration is read from the device tree, > >so document the relevant properties in the binding documentation. > > >diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt > > >+Hardware-triggered thermal reset: > >+On Tegra30, Tegra114 and Tegra124, if the 'i2c-thermtrip' subnode exists, > >+hardware-triggered thermal reset will be enabled. > > "will be enabled" sounds like SW behaviour, whereas DT is suppose to > describe HW, and leave SW to define its own behaviour. I would suggest: > > Optional sub-nodes: > i2c-thermtrip: Describes how to power off the system in the event of a > thermal emergency. > > >+Required properties for hardware-triggered thermal reset (inside 'i2c-thermtrip'): > > Simpler might be: > > Required properties for i2c-thermtrip node: > > >+- nvidia,pmu : Phandle to power management unit / PMIC handling poweroff > >+- nvidia,reg-addr : I2C register address to write poweroff command to > >+- nvidia,reg-data : Poweroff command to write to PMU > > Why are both the PMU/PMIC phandle and the register address/data required? I > thought the purpose of having the phandle was to allow the register address > and data to be queried from the PMU/PMIC driver. > > To me, it seems much simpler to get rid of the phandle and just hard-code > the I2C bus number, address, and data into this node, rather than having to > go query it from the PMU/PMIC driver, then find the I2C controller, then > query it for its ID (and hope that all HW modules that talk to I2C > controllers directly use the same numbering scheme...) I originally requested this to be changed. It seems wrong to duplicate information about the PMIC in both the PMIC device tree node and the i2c-thermtrip node if we can get the same information from the driver directly (via the phandle). It certainly requires a little more code, but at the advantage of not having to figure out the I2C controller hardware number and I2C slave addresses when writing the i2c-thermtrip node. Thierry
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