Hi Stephen,
On 25 July 2016 at 10:50, Stephen Warren swarren@wwwdotorg.org wrote:
On 07/24/2016 08:07 PM, Simon Glass wrote:
Hi Stephen,
On 14 July 2016 at 22:17, Simon Glass sjg@chromium.org wrote:
Hi Stephen,
On 13 July 2016 at 13:45, Stephen Warren swarren@wwwdotorg.org wrote:
From: Stephen Warren swarren@nvidia.com
Many SoCs allow power to be applied to or removed from portions of the SoC (power domains). This may be used to save power. This API provides the means to control such power management hardware.
Signed-off-by: Stephen Warren swarren@nvidia.com
I'll soon(?) send a Tegra186 power domain driver that implements this new subsystem. I'm waiting for all the relevant DT bindings to be reviewed as kernel patches first though.
...
Acked-by: Simon Glass sjg@chromium.org
Could you add a command (with list/on/off subcommands) to control this also?
Any thoughts on this?
Applied to u-boot-dm, thanks!
Such a command sounds like a good idea. I'm a bit too swamped to do this immediately though.
One issue to consider: How would the user specify which power domain to control? There's no global namespace. Only individual drivers can parse their own namespace, and there's no requirement that drivers identify each powerdomain with e.g. a single integer or name, just like DT specificiers can use multiple cells. I can think of two ways to handle this:
a) Add a new "op" function to the driver to allow converting the cmdline arguments the user passed to the shell command into whatever value(s) the driver uses to identify the power domain, e.g. "cmdline_xlate()". This has the disadvantage of requiring extra code (although we could provide a default implementation for the common code), but has the advantage of allowing control over any powerdomain that any driver implements.
b) Make the command take a DT property node name and index, and have the command look the powerdomain ID up from DT. This has the disadvantage of limiting control to powerdomains that are already added to the DT, but does have the advantage of not requiring any driver code.
Option 'b' sounds good. I notice with regulators that there is an extra name in the DT (regulator-name). This is used by the 'pmic' command. Should power domains have that too?
Regards, Simon