Re: [PATCH 0/2] omap_wdt: fix interface clock handling

[Kevin Hilman <khilman@ti.com>]

Kalle Jokiniemi <kalle.jokiniemi@nokia.com> writes:

> The runtime PM does not offer enough granularity to control
> individual clocks separately as needed. Current pm implementation
> of omap_wdt blocks the CORE power domain from idling in
> OMAP SoC, as it keeps the interface clock of the watchdog always
> on. This causes severe power leakage in devices where 
> the omap watchdog is in active use.

The iclk remains active because it's in hardware-controlled
auto-idle mode.  

I believe if you set the WDT hwmod to software-supported idle
(OCPIF_SWSUP_IDLE), the runtime PM idle (which calls omap_device idle,
then omap_hwmod_idle) should also gate the interface clock.

> This patch set reverts the omap_wdt move to runtime_pm and
> introduces a tight control of the interface clock in the driver
> to only enable it when registers are accessed. The patch is
> based on earlier patch by Atal Shargorodsky.
>
> If anyone has good suggestions how to fix this with runtime_pm,
> feel free to propose patches. Otherwise I suggest we revert
> back to something that works.

Can you try with software-supported idle and just making the runtime PM
calls more granular?

Kevin

> Tested with RX-51 S4.0 Macroboard, linux-omap-pm/pm branch and
> MeeGo armv7l release.
>
> Kalle Jokiniemi (2):
>   Revert "OMAP: WDT: Use PM runtime APIs instead of clk FW APIs"
>   Watchdog: omap_wdt: fix interface clock handling
>
>  drivers/watchdog/omap_wdt.c |   64 +++++++++++++++++++++++++++++++++++++------
>  1 files changed, 55 insertions(+), 9 deletions(-)