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

[Shilimkar, Santosh]

On Thu, May 17, 2012 at 5:45 AM, Kevin Hilman <khilman at ti.com> wrote:
> Tero Kristo <t-kristo at ti.com> writes:
>
>> From: Santosh Shilimkar <santosh.shilimkar at ti.com>
>>
>> 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.
>
ok
>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
>> [t-kristo at ti.com: moved workaround from omap-sar.c to pm44xx.c]
>> Signed-off-by: Tero Kristo <t-kristo at ti.com>
>> ---
>>  .../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*
>
ok

>> +             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.
>
Agree. WARN_ON() should suffice.

Regards
santosh