On Wed, Aug 20, 2014 at 02:16:49PM -0600, Stephen Warren wrote:

On 08/13/2014 06:41 AM, Mikko Perttunen wrote:

quoted

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.

quoted

diff --git a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt

quoted

+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.

quoted

+Required properties for hardware-triggered thermal reset (inside 'i2c-thermtrip'):

Simpler might be:

Required properties for i2c-thermtrip node:

quoted

+- 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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20140821/173ffb99/attachment.sig>