Subject: [PATCHv3 8/9] ARM: OMAP2+: AM33XX: Basic suspend resume support

From: [email-masked] (Nishanth Menon)
Date: Wed, 7 Aug 2013 11:22:17 -0500

On 08/06/2013 12:49 PM, Dave Gerlach wrote:
[...]

> +
> +struct forced_standby_module am33xx_mod[] = {
> +	{.oh_name = "usb_otg_hs"},
> +	{.oh_name = "tptc0"},
> +	{.oh_name = "tptc1"},
> +	{.oh_name = "tptc2"},
> +	{.oh_name = "cpgmac0"},
> +};
> +
[...]
> +
> +static int am33xx_pm_suspend(void)
> +{
> +	int i, j, ret = 0;
> +
> +	int status = 0;
> +	struct platform_device *pdev;
> +	struct omap_device *od;
> +
> +	/*
> +	 * By default the following IPs do not have MSTANDBY asserted
> +	 * which is necessary for PER domain transition. If the drivers
> +	 * are not compiled into the kernel HWMOD code will not change the
> +	 * state of the IPs if the IP was not never enabled. To ensure
> +	 * that there no issues with or without the drivers being compiled
> +	 * in the kernel, we forcefully put these IPs to idle.
> +	 */
> +	for (i = 0; i < ARRAY_SIZE(am33xx_mod); i++) {
> +		pdev = to_platform_device(am33xx_mod[i].dev);
> +		od = to_omap_device(pdev);
> +		if (od->_driver_status != BUS_NOTIFY_BOUND_DRIVER) {
> +			omap_device_enable_hwmods(od);
> +			omap_device_idle_hwmods(od);
> +		}
> +	}

Sorry, I dont like this one bit. this is the job of the suspend / resume 
handler dealing with the specific device. I recollect having a similar 
issue on OMAP5 where without USB driver, USB wont idle, hence we cant 
suspend either. is the solution to do a custom handling for specific 
nodes as above? is it even necessary - considering that in multiple 
suspend-resume iterations, do we need to "enable and idle" multiple 
times? Cant we do it just in hwmod/omap_device level where unbound 
devices are disabled? Is there absolutely no possible way to do this in 
a generic manner?

-- 
Regards,
Nishanth Menon