Re: [PATCH 3/5 v3] OMAP3630: PM: Erratum i608: disable RTA

[Kevin Hilman <khilman@deeprootsystems.com>]

Nishanth Menon <nm@ti.com> writes:

> Erratum id: i608
> RTA (Retention Till Access) feature is not supported and leads to device
> stability issues when enabled. This impacts modules with embedded memories
> on OMAP3630
>
> Workaround is to disable RTA on boot and coming out of core off.
> For disabling rta coming out of off mode, we do this by overriding the
> restore pointer for 3630 to allow us restore handler as the first point of
> entry before caches are touched and is common for GP and HS devices.
> to disable earlier than this could be possible by modifying the ppa for HS
> devices, but not for GP devices.
>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> Cc: Tony Lindgren <tony@atomide.com>
>
> [ambresh@ti.com: co-developer]
> Signed-off-by: Ambresh K <ambresh@ti.com>
> Signed-off-by: Nishanth Menon <nm@ti.com>

[...]

> @@ -1045,6 +1057,15 @@ static int __init omap3_pm_init(void)
>  	pm_idle = omap3_pm_idle;
>  	omap3_idle_init();
>  
> +	/*
> +	 * RTA is disabled during initialization as per erratum i608
> +	 * it is safer to disable rta by the bootloader, but we would like
> +	 * to be doubly sure here and prevent any mishaps.
> +	 */
> +	if (IS_PM34XX_ERRATUM(RTA_ERRATUM_i608))
> +		omap_ctrl_writel(OMAP36XX_RTA_DISABLE,
> +			OMAP36XX_CONTROL_MEM_RTA_CTRL);
> +

Minor nit: we've been trying to clean up control module access.  So,
rather than directly writing control module registers, could you create
an API for this like was done for omap3_ctrl_write_boot_mode().

Thanks,

Kevin