Subject: [PATCHv2 15/19] ARM: OMAP4430: PM: workaround for DDR corruption on second CS

From: [email-masked] (Kevin Hilman)
Date: Wed, 16 May 2012 17:15:09 -0700

Tero Kristo <[email-masked]> writes:

> From: Santosh Shilimkar <[email-masked]>
>
> Work around for Errata ID: i632 "LPDDR2 Corruption After OFF Mode
> Transition When CS1 Is Used On EMIF" which impacts OMAP443x silicon
> The issue occurs when EMIF_SDRAM_CONFIG is restored first before
> EMIF_SDRAM_CONFIG_2 is not yet restored, the register configuration
> is not set properly, we apply the required workaround allowing
> the restore sequence to work properly.

Please summarize the workaround here as well.

> Signed-off-by: Santosh Shilimkar <[email-masked]>
> [t-kristo at ti.com: moved workaround from omap-sar.c to pm44xx.c]
> Signed-off-by: Tero Kristo <[email-masked]>
> ---
>  .../include/mach/ctrl_module_wkup_44xx.h           |    2 +
>  arch/arm/mach-omap2/pm44xx.c                       |   37 ++++++++++++++++++++
>  2 files changed, 39 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/include/mach/ctrl_module_wkup_44xx.h b/arch/arm/mach-omap2/include/mach/ctrl_module_wkup_44xx.h
> index a0af9ba..b763a79 100644
> --- a/arch/arm/mach-omap2/include/mach/ctrl_module_wkup_44xx.h
> +++ b/arch/arm/mach-omap2/include/mach/ctrl_module_wkup_44xx.h
> @@ -28,6 +28,8 @@
>  #define OMAP4_CTRL_MODULE_WKUP_IP_REVISION		0x0000
>  #define OMAP4_CTRL_MODULE_WKUP_IP_HWINFO		0x0004
>  #define OMAP4_CTRL_MODULE_WKUP_IP_SYSCONFIG		0x0010
> +#define OMAP4_CTRL_SECURE_EMIF1_SDRAM_CONFIG2_REG	0x0114
> +#define OMAP4_CTRL_SECURE_EMIF2_SDRAM_CONFIG2_REG	0x011c
>  #define OMAP4_CTRL_MODULE_WKUP_CONF_DEBUG_SEL_TST_0	0x0460
>  #define OMAP4_CTRL_MODULE_WKUP_CONF_DEBUG_SEL_TST_1	0x0464
>  #define OMAP4_CTRL_MODULE_WKUP_CONF_DEBUG_SEL_TST_2	0x0468
> diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
> index 215b80e..dfaa254 100644
> --- a/arch/arm/mach-omap2/pm44xx.c
> +++ b/arch/arm/mach-omap2/pm44xx.c
> @@ -17,12 +17,18 @@
>  #include <linux/err.h>
>  #include <linux/slab.h>
>  #include <asm/system_misc.h>
> +#include <linux/io.h>
> +
> +#include <mach/ctrl_module_wkup_44xx.h>
> +#include <mach/hardware.h>
>  
>  #include "common.h"
>  #include "clockdomain.h"
>  #include "powerdomain.h"
>  #include "pm.h"
>  
> +#define EMIF_SDRAM_CONFIG2_OFFSET	0xc
> +
>  struct power_state {
>  	struct powerdomain *pwrdm;
>  	u32 next_state;
> @@ -215,6 +221,37 @@ static int __init omap4_pm_init(void)
>  
>  	pr_err("Power Management for TI OMAP4.\n");
>  
> +	/*
> +	 * Work around for OMAP443x Errata i632: "LPDDR2 Corruption After OFF
> +	 * Mode Transition When CS1 Is Used On EMIF":
> +	 * Overwrite EMIF1/EMIF2
> +	 * SECURE_EMIF1_SDRAM_CONFIG2_REG
> +	 * SECURE_EMIF2_SDRAM_CONFIG2_REG
> +	 */
> +	if (cpu_is_omap443x()) {

This should probably be done later in this function, after PM_ERRATUM
flags are setup, and then it should use a PM_ERRATUM flag instead of cpu_is*

> +		void __iomem *secure_ctrl_mod;
> +		void __iomem *emif1;
> +		void __iomem *emif2;
> +		u32 val;
> +
> +		secure_ctrl_mod = ioremap(OMAP4_CTRL_MODULE_WKUP, SZ_4K);
> +		emif1 = ioremap(OMAP44XX_EMIF1_BASE, SZ_1M);
> +		emif2 = ioremap(OMAP44XX_EMIF2_BASE, SZ_1M);
> +
> +		BUG_ON(!secure_ctrl_mod || !emif1 || !emif2);

Please avoid BUG_ON() and use proper error recovery.  This is not a
condition where the entire kernel should panic.

> +		val = __raw_readl(emif1 + EMIF_SDRAM_CONFIG2_OFFSET);
> +		__raw_writel(val, secure_ctrl_mod +
> +			     OMAP4_CTRL_SECURE_EMIF1_SDRAM_CONFIG2_REG);
> +		val = __raw_readl(emif2 + EMIF_SDRAM_CONFIG2_OFFSET);
> +		__raw_writel(val, secure_ctrl_mod +
> +			     OMAP4_CTRL_SECURE_EMIF2_SDRAM_CONFIG2_REG);
> +		wmb();
> +		iounmap(secure_ctrl_mod);
> +		iounmap(emif1);
> +		iounmap(emif2);
> +	}
>
>  	ret = pwrdm_for_each(pwrdms_setup, NULL);
>  	if (ret) {
>  		pr_err("Failed to setup powerdomains\n");

Kevin