Re: omap3isp as a wakeup source

[Tero Kristo <t-kristo@ti.com>]

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@iki.fi> 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


Texas Instruments Oy, Tekniikantie 12, 02150 Espoo. Y-tunnus: 0115040-6. Kotipaikka: Helsinki