Re: [PATCHv4 8/8] ARM: OMAP3: do not delete per_clkdm autodeps during idle

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

On Tue, 2012-09-18 at 22:25 +0000, Paul Walmsley wrote:
> Hi Tero,
> 
> just looking at the usecounting series to see what is mergeable and 
> noticed this:
> 
> On Fri, 13 Jul 2012, Tero Kristo wrote:
> 
> > Secondly, there are multiple erratas for omap3, which say that the 
> > wakedeps should be enabled for the PER domain, see e.g. errata i582 for 
> > omap3630.
> 
> Erratum i582 mentions that a wakeup dependency needs to exist between PER 
> and WKUP such that PER will wake when CORE_L3 does.  Our autodeps would 
> not add this dependency; they just would attempt to add a wakeup 
> dependency between PER and MPU/IVA2.  So we need a different mechanism.  
> What do you think about the following patch to handle part of the i582 
> workaround?

Yes, that looks good to me, someone will need to test it though.

> 
> Also, do you have any of the other errata information handy, so we can 
> track those down also?  I'm pretty sure we need to enable the wakeup 
> dependency between PER and CORE also for OMAP3, but can't recall the 
> reference.

GPIO errata i467 has a workaround which involves wakedeps. i582 is valid
for omap3430 also. I am not able to find anything else regarding
wakedeps right now, at least nothing regarding per vs core.

-Tero

> 
> 
> - Paul
> 
> From: Paul Walmsley <paul@pwsan.com>
> Date: Tue, 18 Sep 2012 16:02:38 -0600
> Subject: [PATCH] ARM: OMAP36xx: PM: apply part of the erratum i582 workaround
> 
> On OMAP36xx chips with ES < 1.2, if the PER powerdomain goes to OSWR
> or OFF while CORE stays at CSWR or ON, or if, upon chip wakeup from
> OSWR or OFF, the CORE powerdomain goes ON before PER, the UART3/4
> FIFOs and McBSP2/3 SIDETONE memories will be unusable.  This is
> erratum i582 in the OMAP36xx Silicon Errata document.
> 
> This patch implements one of several parts of the workaround: the
> addition of the wakeup dependency between the PER and WKUP
> clockdomains, such that PER will wake up at the same time CORE_L3
> does.
> 
> This is not a complete workaround.  For it to be complete:
> 
> 1. the PER powerdomain's next power state must not be set to OSWR or
>    OFF if the CORE powerdomain's next power state is set to CSWR or
>    ON;
> 
> 2. the UART3/4 FIFO and McBSP2/3 SIDETONE loopback tests should be run
>    if the LASTPOWERSTATEENTERED bits for PER and CORE indicate that
>    PER went OFF while CORE stayed on.  If loopback tests fail, then
>    those devices will be unusable until PER and CORE can undergo a
>    transition from ON to OSWR/OFF and back ON.
> 
> Signed-off-by: Paul Walmsley <paul@pwsan.com>
> Cc: Tero Kristo <t-kristo@ti.com>
> Cc: Kevin Hilman <khilman@ti.com>
> ---
>  arch/arm/mach-omap2/pm.h     |    1 +
>  arch/arm/mach-omap2/pm34xx.c |   24 +++++++++++++++++++++++-
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
> index 686137d..67d6613 100644
> --- a/arch/arm/mach-omap2/pm.h
> +++ b/arch/arm/mach-omap2/pm.h
> @@ -91,6 +91,7 @@ extern void omap3_save_scratchpad_contents(void);
>  
>  #define PM_RTA_ERRATUM_i608		(1 << 0)
>  #define PM_SDRC_WAKEUP_ERRATUM_i583	(1 << 1)
> +#define PM_PER_MEMORIES_ERRATUM_i582	(1 << 2)
>  
>  #if defined(CONFIG_PM) && defined(CONFIG_ARCH_OMAP3)
>  extern u16 pm34xx_errata;
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index 05bd8f0..5e99345 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -651,7 +651,8 @@ static void __init pm_errata_configure(void)
>  		/* Enable the l2 cache toggling in sleep logic */
>  		enable_omap3630_toggle_l2_on_restore();
>  		if (omap_rev() < OMAP3630_REV_ES1_2)
> -			pm34xx_errata |= PM_SDRC_WAKEUP_ERRATUM_i583;
> +			pm34xx_errata |= (PM_SDRC_WAKEUP_ERRATUM_i583 |
> +					  PM_PER_ERRATUM_i582);
>  	}
>  }
>  
> @@ -726,6 +727,27 @@ int __init omap3_pm_init(void)
>  	if (IS_PM34XX_ERRATUM(PM_RTA_ERRATUM_i608))
>  		omap3630_ctrl_disable_rta();
>  
> +	/*
> +	 * The UART3/4 FIFO and the sidetone memory in McBSP2/3 are
> +	 * not correctly reset when the PER powerdomain comes back
> +	 * from OFF or OSWR when the CORE powerdomain is kept active.
> +	 * See OMAP36xx Erratum i582 "PER Domain reset issue after
> +	 * Domain-OFF/OSWR Wakeup".  This wakeup dependency is not a
> +	 * complete workaround.  The kernel must also prevent the PER
> +	 * powerdomain from going to OSWR/OFF while the CORE
> +	 * powerdomain is not going to OSWR/OFF.  And if PER last
> +	 * power state was off while CORE last power state was ON, the
> +	 * UART3/4 and McBSP2/3 SIDETONE devices need to run a
> +	 * self-test using their loopback tests; if that fails, those
> +	 * devices are unusable until the PER/CORE can complete a transition
> +	 * from ON to OSWR/OFF and then back to ON.
> +	 *
> +	 * XXX Technically this workaround is only needed if off-mode
> +	 * or OSWR is enabled.
> +	 */
> +	if (IS_PM34XX_ERRATUM(PM_PER_MEMORIES_ERRATUM_i582))
> +		clkdm_add_wkdep(per_clkdm, wkup_clkdm);
> +
>  	clkdm_add_wkdep(neon_clkdm, mpu_clkdm);
>  	if (omap_type() != OMAP2_DEVICE_TYPE_GP) {
>  		omap3_secure_ram_storage =