Re: [PATCH] OMAP3: PM: Force USB to standby if not used

[Kevin Hilman <khilman@deeprootsystems.com>]

Tero Kristo <tero.kristo@nokia.com> writes:

> From: Tero Kristo <tero.kristo@nokia.com>
>
> This patch will allow device to enter sleep mode while a USB cable is
> connected and USB is either disabled or built as a module from kernel
> config.
>
> Applies on top of PM branch.
>
> Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
> ---
>  arch/arm/mach-omap2/usb-musb.c |   10 ++++++++--
>  1 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/usb-musb.c b/arch/arm/mach-omap2/usb-musb.c
> index 12a9b0a..dd51d2f 100644
> --- a/arch/arm/mach-omap2/usb-musb.c
> +++ b/arch/arm/mach-omap2/usb-musb.c
> @@ -32,7 +32,9 @@
>  #include <mach/usb.h>
>  
>  #define AUTOIDLE        (1 << 0)
> +#define FORCESTDBY	(1 << 0)
>  #define OTG_SYSCONFIG	(OMAP34XX_HSUSB_OTG_BASE + 0x404)
> +#define OTG_FORCESTDBY	(OMAP34XX_HSUSB_OTG_BASE + 0x414)
>  
>  static struct resource musb_resources[] = {
>  	[0] = { /* start and end set dynamically */
> @@ -185,7 +187,11 @@ void __init usb_musb_init(void)
>  		return;
>  	}
>  
> -	/* Enable smartidle on MUSB to improve C1 wakeup latency */
> -	if (cpu_is_omap34xx())
> +#if !defined(CONFIG_USB) || defined(CONFIG_USB_MODULE)
> +	/* Force MUSB to standby if not used */
> +	if (cpu_is_omap34xx()) {
>  		omap_writel(AUTOIDLE, OTG_SYSCONFIG);
> +		omap_writel(FORCESTDBY, OTG_FORCESTDBY);
> +	}
> +#endif

Tero,

Is this needed if OTG_SYSCONFIG is set to force-idle?

Yesterday, I pushed a patch changing OTG_SYSCONFIG to force-idle
instead of auto-idle since on ES3.0 3430SDP, having it in auto-idle
was keeping CORE from hitting retention.  IIUC, there's an errata
where force-idle doesn't work properly.

Also, why the #ifdefs?

This code is already conditionally compiled based on
CONFIG_USB_MUSB_SOC (see mach-omap2/Makefile) which is set whether
MUSB is built-in or a module.

#if !defined(CONFIG_USB) then CONFIG_USB_MUSB_SOC will not be defined
either.

Kevin