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* [QUERY] AMBA: PM domains when !CONFIG_PM
@ 2016-06-16 11:19 Sudeep Holla
       [not found] ` <CAPDyKFoV5Y1mHuDZmWgynCicux2deV89npp-siTQDJr0uZFwcg@mail.gmail.com>
  0 siblings, 1 reply; 2+ messages in thread
From: Sudeep Holla @ 2016-06-16 11:19 UTC (permalink / raw)
  To: linux-arm-kernel

Hi Ulf, Kevin,

I have a situation where we need to enable the power domain to access an
AMBA device. This is all fine with patches from Ulf and Marek in amba/bus.c

The problem is when we disable CONFIG_PM, dev_pm_domain_attach
returns -ENODEV irrespective of whether a DT node has a PM domain
in it or not. If dev_pm_domain_attach returns anything other than
-EPROBE_DEFER, we ignore the error and proceed to access the device
which will explode.

Basically, we need a way to prevent addition of that amba device if DT
node has PD specified but CONFIG_PM=n. Any thoughts ?

-- 
Regards,
Sudeep

^ permalink raw reply	[flat|nested] 2+ messages in thread

• [parent not found: <CAPDyKFoV5Y1mHuDZmWgynCicux2deV89npp-siTQDJr0uZFwcg@mail.gmail.com>]

• • * [QUERY] AMBA: PM domains when !CONFIG_PM
           [not found] ` <CAPDyKFoV5Y1mHuDZmWgynCicux2deV89npp-siTQDJr0uZFwcg@mail.gmail.com>
    @ 2016-06-16 12:47   ` Sudeep Holla
      0 siblings, 0 replies; 2+ messages in thread
    From: Sudeep Holla @ 2016-06-16 12:47 UTC (permalink / raw)
      To: linux-arm-kernel
    
    
    
    On 16/06/16 13:33, Ulf Hansson wrote:
    >
    >
    > On 16 June 2016 at 13:19, Sudeep Holla <sudeep.holla@arm•com
    > <mailto:sudeep.holla@arm•com>> wrote:
    >
    >     Hi Ulf, Kevin,
    >
    >     I have a situation where we need to enable the power domain to access an
    >     AMBA device. This is all fine with patches from Ulf and Marek in
    >     amba/bus.c
    >
    >     The problem is when we disable CONFIG_PM, dev_pm_domain_attach
    >     returns -ENODEV irrespective of whether a DT node has a PM domain
    >     in it or not. If dev_pm_domain_attach returns anything other than
    >     -EPROBE_DEFER, we ignore the error and proceed to access the device
    >     which will explode.
    >
    >     Basically, we need a way to prevent addition of that amba device if DT
    >     node has PD specified but CONFIG_PM=n. Any thoughts ?
    >
    >
    > The solution TEGRA picked for a kind of similar issue was to enable
    > CONFIG_PM for a family of SoCs.
    >
    > I assume this would be applicable here as well, or are you saying this
    > platform actually is able to work *without* PM support?
    >
    
    I agree, but if someone tries to boot with !CONFIG_PM, it just hangs
    without a clue, hence I raised this query. I am fine by forcing it to be
    ON always, but just wanted to check if this is something serious that it
    needs to be addressed.
    
    Thanks for the quick response.
    
    -- 
    Regards,
    Sudeep
    
    ^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2016-06-16 12:47 UTC | newest]

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2016-06-16 11:19 [QUERY] AMBA: PM domains when !CONFIG_PM Sudeep Holla
     [not found] ` <CAPDyKFoV5Y1mHuDZmWgynCicux2deV89npp-siTQDJr0uZFwcg@mail.gmail.com>
2016-06-16 12:47   ` Sudeep Holla

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