On Tue, Sep 13, 2011 at 11:48 AM, Tero Kristo <t-kristo@xxxxxx> wrote:
> On Tue, 2011-09-13 at 08:49 +0200, Sakari Ailus wrote:
>> anish singh wrote:
>> > On Tue, Sep 13, 2011 at 1:58 AM, Sakari Ailus <sakari.ailus@xxxxxx> wrote:
>> >> On Mon, Sep 12, 2011 at 04:50:42PM +0200, Enrico wrote:
>> >>> Hi,
>> >>
>> >> Hi Enrico,
>> >>
>> >>> While testing omap3isp+tvp5150 with latest Deepthy bt656 patches
>> >>> (kernel 3.1rc4) i noticed that yavta hangs very often when grabbing
>> >>> or, if not hanged, it grabs at max ~10fps.
>> >>>
>> >>> Then i noticed that tapping on the (serial) console made it "unblock"
>> >>> for some frames, so i thought it doesn't prevent the cpu to go
>> >>> idle/sleep. Using the boot arg "nohlt" the problem disappear and it
>> >>> grabs at a steady 25fps.
>> >>>
>> >>> In the code i found a comment that says the camera can't be a wakeup
>> >>> source but the camera powerdomain is instead used to decide to not go
>> >>> idle, so at this point i think the camera powerdomain is not enabled
>> >>> but i don't know how/where to enable it. Any ideas?
>> >>
>> >> I can confirm this indeed is the case --- ISP can't wake up the system ---
>> >> but don't know how to prevent the system from going to sleep when using the
>> >> ISP.
>> > Had it been on android i think wakelock would have been very useful.
>>
>> I believe there are proper means to do this using more standard methods
>> as well. Not being a PM expert, I don't know how.
>>
>> Cc Tero.
>>
>
> Hi,
>
> I don't think there are proper means yet to do this, as camera is
> somewhat a special case in omap3, it is apparently the only module that
> is causing this kind of problem. However, you can prevent idle when
> camera is active with something like this:
>
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index 2789e0a..7fdf6e2 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -358,6 +358,9 @@ void omap_sram_idle(void)
> omap3_per_save_context();
> }
>
> + if (pwrdm_read_pwrst(cam_pwrdm) == PWRDM_POWER_ON)
> + clkdm_deny_idle(mpu_pwrdm->pwrdm_clkdms[0]);
> +
> /* CORE */
> if (core_next_state < PWRDM_POWER_ON) {
> omap_uart_prepare_idle(0);
>
>
>
> -Tero
i think something related is already in
arch/arm/mach-omap2/cpuidle34xx.c omap3_enter_idle_bm(...):
/*
* Prevent idle completely if CAM is active.
* CAM does not have wakeup capability in OMAP3.
*/
cam_state = pwrdm_read_pwrst(cam_pd);
if (cam_state == PWRDM_POWER_ON) {
new_state = dev->safe_state;
goto select_state;
}
But probably the power domain is not set to ON, and i don't know where
it should be set. Maybe, as Laurent suggested, adding runtime PM
support will fix it?
Thanks,
Enrico
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