From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rajendra Nayak <rnayak@ti.com>
Date: Mon, 25 Jun 2012 12:54:50 +0000
Subject: Re: [PATCH] OMAPDSS: Check if RPM enabled before trying to change state
Message-Id: <4FE85CCA.80903@ti.com>
List-Id: <linux-fbdev.vger.kernel.org>
References: <1340438771-25587-1-git-send-email-jaswinder.singh@linaro.org>	 <1340605221.12683.30.camel@lappyti>	 <CANOLnOOodXtqV7Hs-SsEUfB3Uo1PSGb8bkaeN7M48jVpQrb-cA@mail.gmail.com> <1340627459.3395.54.camel@deskari>
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To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Grazvydas Ignotas <notasas@gmail.com>, jaswinder.singh@linaro.org, mythripk@ti.com, linux-omap@vger.kernel.org, linux-fbdev@vger.kernel.org, andy.green@linaro.org, n-dechesne@ti.com

On Monday 25 June 2012 06:00 PM, Tomi Valkeinen wrote:
> On Mon, 2012-06-25 at 15:05 +0300, Grazvydas Ignotas wrote:
>> On Mon, Jun 25, 2012 at 9:20 AM, Tomi Valkeinen<tomi.valkeinen@ti.com>  wrote:
>>> On Sat, 2012-06-23 at 13:36 +0530, jaswinder.singh@linaro.org wrote:
>>>>
>>>>   Currenlty HDMI fails to come up in the suspend-resume path.
>>>> This patch helps that real-world scenario.
>>>
>>> What is the problem there? It'd be good to explain the problem in the
>>> patch description. Does the pm_runtime_get return -EACCES?
>>
>> On slightly different but related issue, currently OMAPDSS always
>> spits lots of backtraces when it's compiled without CONFIG_PM_RUNTIME,
>> because pm_runtime_put* always return -ENOSYS without
>> CONFIG_PM_RUNTIME. So something like this patch proposes is needed, or
>> maybe WARN_ON should check for -ENOSYS, I don't know..
>
> Hmm. I guess I'm missing some understanding about runtime PM. omapdss
> uses runtime PM to enable the underlying DSS hardware. If there's no
> runtime PM, how does the driver work? Or is it the job of
> hwmod/omap_device to keep all the hardware always enabled if runtime PM
> is not compiled in?

Yes, the below trick keeps all hwmods always enabled post the initial
setup if runtime PM is disabled.

from arch/arm/mach-omap2/io.c

static void __init omap_hwmod_init_postsetup(void)
{
         u8 postsetup_state;

         /* Set the default postsetup state for all hwmods */
#ifdef CONFIG_PM_RUNTIME
         postsetup_state = _HWMOD_STATE_IDLE;
#else
         postsetup_state = _HWMOD_STATE_ENABLED;
#endif
         omap_hwmod_for_each(_set_hwmod_postsetup_state, &postsetup_state);

         omap_pm_if_early_init();
}

>
>   Tomi
>