[PATCH v4 13/21] ARM: omap: convert wakeupgen to stacked domains

On 1/21/2015 12:43 PM, Tony Lindgren wrote:

* santosh shilimkar [off-list ref] [150121 12:16]:

quoted

On 1/21/2015 10:36 AM, Tony Lindgren wrote:

quoted

* Marc Zyngier [off-list ref] [150121 09:25]:

quoted

On 21/01/15 16:30, Tony Lindgren wrote:

quoted

I gave this a quick boot test on am437x-gp-evm and the
interrupts look OK with the fix also applied:

# cat /proc/interrupts
             CPU0
  16:        657     WUGEN  68  gp_timer
  18:          0     WUGEN   9  l3-dbg-irq
  19:          0     WUGEN  10  l3-app-irq
  20:          5     WUGEN  12  edma
  22:          0     WUGEN  14  edma_error
  23:         96     WUGEN  72  OMAP UART0
  33:          0  44e07000.gpio   6  mmc0
158:         52     WUGEN  70  44e0b000.i2c
159:          0     WUGEN  71  4802a000.i2c
160:         35     WUGEN  64  mmc0
161:          0     WUGEN  40  4a100000.ethernet
162:       7739     WUGEN  41  4a100000.ethernet
163:       7608     WUGEN  42  4a100000.ethernet
164:          0     WUGEN  43  4a100000.ethernet
170:          0     WUGEN 100  gpmc
180:          0     WUGEN   7  tps65218
IPI0:          0  CPU wakeup interrupts
IPI1:          0  Timer broadcast interrupts
IPI2:          0  Rescheduling interrupts
IPI3:          0  Function call interrupts
IPI4:          0  Single function call interrupts
IPI5:          0  CPU stop interrupts
IPI6:          0  IRQ work interrupts
IPI7:          0  completion interrupts
Err:          0

Interesting. No TWD timer on this one?

Good question, adding Felipe to cc. It eems to be there in
the TRM in "Table 2-3.  L4_PER Peripheral Memory Map" as
MPU_PRV_TIMERS. Also seems to actually work with the
attached patch:

TWD is useless on this machine since single core and TWD
as know die in low power states. All the broadcast stuff
is for SMP machines.

Hmm it seems we should still use TWD during runtime and
swich over to the gptimer for idle states for wake-up
events.

Well timer wheel code don't support it so if you are serious,
some one needs to do that. For me, it is not worth at all.
You will have more to loose than gain with these time switching
schemes since you have to keep 2 times alive, do switching, loose
the idle time.

All of that is to save few CPU cycles since TWD is closer
compared to other SOC timer.

Anyways I will let you fight it out but IIRC, I had a
discussion a while back with tglx in one of the conference
and the conclusion was it not worth doing.
Rather TWD hardware on SOC should be made wakeup capable
and then everything is good.

Till you have support, using TWD on AM43XX will break CPUIDLE.
Not sure if it is supported or some one cares about it. Just
keep that aspect in mind.

Regards,
Santosh