On Fri, 27 Feb 2015, Robert Jarzmik wrote:

Lee Jones [off-list ref] writes:

quoted

v2 => v3:
  - Ensure DT actually reflects h/w
    - i.e. Nodes should not contain a mishmash of different IP
      blocks, but should identify related h/w.  In the current
      example we use interconnects
  - Change naming from clkdomain to clk-always-on
  - Place "do not abuse" warning in documentation

v1 => v2:
  - Turned the ST specific driver into a generic one
  
Hardware can have a bunch of clocks which must not be turned off.
If drivers a) fail to obtain a reference to any of these or b) give
up a previously obtained reference during suspend, the common clk
framework will attempt to turn them off and the hardware will
subsequently die.  The only way to recover from this failure is to
restart.
  
To avoid either of these two scenarios from catastrophically
disabling the running system we have implemented a clock domain
where clocks are consumed and references are taken, thus preventing
them from being shut down by the framework.

Hi Lee,

I wonder why there is a need for a new clock when CLK_IGNORE_UNUSED does
exist. What is the usecase that is covered by this patchset which is not used by
CLK_IGNORE_UNUSED clock flag ?

And if that reason exists, I'd like to find it in the commit message.

The problem is applying that flag in a generic way.

However, I guess you haven't seen this [1] yet?

[1] https://lkml.org/lkml/2015/2/27/548

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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