Re: [PATCH 5/6] ARM: OMAP4: CLKDM: Update supported transition modes

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Hi Jon,

On 5/15/2012 4:33 PM, Jon Hunter wrote:
Hi Santosh, Benoit,

On 05/10/2012 01:54 AM, Santosh Shilimkar wrote:
On Thursday 10 May 2012 03:06 AM, Jon Hunter wrote:
From: Jon Hunter<jon-hunter@xxxxxx>

For OMAP3+ devices, the clock domains (CLKDMs) support one or more of the
following transition modes ...

NO_SLEEP (0x0) - A clock domain sleep transition is never initiated,
		 irrespective of the hardware conditions.
SW_SLEEP (0x1) - A software-forced sleep transition. The transition is initiated
		 when the associated hardware conditions are satisfied
SW_WKUP  (0x2) - A software-forced clock domain wake-up transition is initiated,
		 irrespective of the hardware conditions.
HW_AUTO  (0x3) - Hardware-controlled automatic sleep and wake-up transition is
		 initiated by the PRCM module when the associated hardware
		 conditions are satisfied.

For OMAP4 devices, SW_SLEEP is equivalent to HW_AUTO and NO_SLEEP is equivalent
to SW_WKUP. For OMAP4 devices, all CLKDMs support HW_AUTO and therefore we can
place the CLKDMs in the HW_AUTO state instead of the SW_SLEEP mode. Hence, we
do not need to use the SW_SLEEP mode. With regard to NO_SLEEP and SW_WKUP it is
preferred to use SW_WKUP mode if the CLKDM supports it and so use this mode
instead of NO_SLEEP where possible.

For a software perspective the above 4 modes are represented by the following
flags to indicate what modes are supported by each of the CLKDMs.

CLKDM_CAN_DISABLE_AUTO	-->  NO_SLEEP
CLKDM_CAN_ENABLE_AUTO	-->  HW_AUTO
CLKDM_CAN_FORCE_SLEEP	-->  SW_SLEEP
CLKDM_CAN_FORCE_WAKEUP	-->  SW_WKUP

By eliminating the SW_SLEEP mode the the mapping of the flags for OMAP4 devices
can becomes ...

CLKDM_CAN_DISABLE_AUTO	-->  NO_SLEEP
CLKDM_CAN_ENABLE_AUTO	-->  HW_AUTO
CLKDM_CAN_FORCE_SLEEP	-->  HW_AUTO
Not sure if this can be entirely correct for OMAP4.
Because HW_AUTO = "Sleep and wakeup transition are
based upon hardware conditions"
Where as SW_SLEEP = "Start a software forced sleep
transition on the domain."

I will reply on the the thread where this is being discussed.

Given that feedback we received that the only difference between HW_AUTO
and SW_SLEEP is "that the PRM_IRQSTATUS_MPU.TRANSITION_ST interrupt
status is set in case of SW_SLEEP transition, and not set in case of
HW_AUTO transition". Are you ok with this change? If so can you sign-off
on this?

Yep I'm OK with that, but Paul is the only one who can sign-off this patch.

Reviewed-by: Benoit Cousson <b-cousson@xxxxxx>

Regards,
Benoit
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