Subject: [PATCH 1/1] ARM: OMAP2+: Fix omap3 off idle power consumption creeping up

From: [email-masked] (Nishanth Menon)
Date: Tue, 21 Apr 2015 21:09:18 -0500

On 04/21/2015 08:00 PM, Tony Lindgren wrote:
> * Nishanth Menon <[email-masked]> [150421 15:13]:
>> On 14:47-20150421, Tony Lindgren wrote:
>>> * Tony Lindgren <[email-masked]> [150421 09:24]:
>>>> If we use a combination of VMODE and I2C4 for retention modes,
>>>> eventually the off idle power consumption will creep up by about
>>>> 23mW, even during off mode with I2C4 always staying enabled.
>>>>
>>>> Looks like the only way to fix the extra power consumption is to
>>>> disable I2C4 usage by setting SEL_VMODE for both off idle and
>>>> retention idle. Let's also update the comments accordingly.
>>>
>>> Thanks Nishanth for pointing me to the related SmartReflex I2C4
>>> erratum. No need to disable I2C4 with the SREN workaround :)
>>>
>>> Better patch below, presumably this only affects omap3?
>>
>> SREN applies to both OMAP3 and 4 - so, the patch looks right.
> 
> Oh OK, I was missing setting the clear bit for omap4. I've added
> it now.
>  
>>> If we use a combination of VMODE and I2C4 for retention modes,
>>> eventually the off idle power consumption will creep up by about
>>> 23mW, even during off mode with I2C4 always staying enabled.
>>>
>>> Turns out this is because of erratum 2.11 "Extra Power Consumed
>> I suggest using the unique ID
>>
>> i531 - that remains constant across SoCs.
> 
> OK thanks, updated patch below.
> 
> Regards,
> 
> Tony
> 
> 8< ------------------
> From: Tony Lindgren <[email-masked]>
> Date: Tue, 21 Apr 2015 14:31:23 -0700
> Subject: [PATCH] ARM: OMAP2+: Fix omap off idle power consumption creeping up
> 
> If we use a combination of VMODE and I2C4 for retention modes,
> eventually the off idle power consumption will creep up by about
> 23mW, even during off mode with I2C4 always staying enabled.
> 
> Turns out this is because of erratum i531 "Extra Power Consumed
> When Repeated Start Operation Mode Is Enabled on I2C Interface
> Dedicated for Smart Reflex (I2C4)" as pointed out by Nishanth
> Menon <[email-masked]>.
> 
> Let's fix the issue by adding i2c_cfg_clear_mask for the bits
> to clear when initializing the I2C4 adapter so we can clear
> SREN bit that drives the I2C4 lines low otherwise when there
> is no traffic.
> 
> Fixes: 3b8c4ebb7630 ("ARM: OMAP3: Fix idle mode signaling for
> sys_clkreq and sys_off_mode")
> Cc: Kevin Hilman <[email-masked]>
> Cc: Nishanth Menon <[email-masked]>
> Cc: Tero Kristo <[email-masked]>
> Signed-off-by: Tony Lindgren <[email-masked]>
> 
> --- a/arch/arm/mach-omap2/prm-regbits-34xx.h
> +++ b/arch/arm/mach-omap2/prm-regbits-34xx.h
> @@ -112,6 +112,7 @@
>  #define OMAP3430_VC_CMD_ONLP_SHIFT			16
>  #define OMAP3430_VC_CMD_RET_SHIFT			8
>  #define OMAP3430_VC_CMD_OFF_SHIFT			0
> +#define OMAP3430_SREN_MASK				(1 << 4)
>  #define OMAP3430_HSEN_MASK				(1 << 3)
>  #define OMAP3430_MCODE_MASK				(0x7 << 0)
>  #define OMAP3430_VALID_MASK				(1 << 24)
> --- a/arch/arm/mach-omap2/prm-regbits-44xx.h
> +++ b/arch/arm/mach-omap2/prm-regbits-44xx.h
> @@ -35,6 +35,7 @@
>  #define OMAP4430_GLOBAL_WARM_SW_RST_SHIFT				1
>  #define OMAP4430_GLOBAL_WUEN_MASK					(1 << 16)
>  #define OMAP4430_HSMCODE_MASK						(0x7 << 0)
> +#define OMAP4430_SRMODEEN_MASK						(1 << 4)
>  #define OMAP4430_HSMODEEN_MASK						(1 << 3)
>  #define OMAP4430_HSSCLL_SHIFT						24
>  #define OMAP4430_ICEPICK_RST_SHIFT					9
> --- a/arch/arm/mach-omap2/vc.c
> +++ b/arch/arm/mach-omap2/vc.c
> @@ -316,7 +316,8 @@ static void __init omap3_vc_init_pmic_signaling(struct voltagedomain *voltdm)
>  	 * idle. And we can also scale voltages to zero for off-idle.
>  	 * Note that no actual voltage scaling during off-idle will
>  	 * happen unless the board specific twl4030 PMIC scripts are
> -	 * loaded.
> +	 * loaded. See also omap_vc_i2c_init for comments regarding
> +	 * erratum i531.
>  	 */
>  	val = voltdm->read(OMAP3_PRM_VOLTCTRL_OFFSET);
>  	if (!(val & OMAP3430_PRM_VOLTCTRL_SEL_OFF)) {
> @@ -704,9 +705,16 @@ static void __init omap_vc_i2c_init(struct voltagedomain *voltdm)
>  		return;
>  	}
>  
> +	/*
> +	 * Note that for omap3 OMAP3430_SREN_MASK clears SREN to work around
> +	 * erratum i531 "Extra Power Consumed When Repeated Start Operation
> +	 * Mode Is Enabled on I2C Interface Dedicated for Smart Reflex (I2C4)".
> +	 * Otherwise I2C4 eventually leads into about 23mW extran power being
nitpick: extran ;)

> +	 * consumed even during off idle using VMODE.
> +	 */
>  	i2c_high_speed = voltdm->pmic->i2c_high_speed;
>  	if (i2c_high_speed)
> -		voltdm->rmw(vc->common->i2c_cfg_hsen_mask,
> +		voltdm->rmw(vc->common->i2c_cfg_clear_mask,
>  			    vc->common->i2c_cfg_hsen_mask,
>  			    vc->common->i2c_cfg_reg);
>  
> --- a/arch/arm/mach-omap2/vc.h
> +++ b/arch/arm/mach-omap2/vc.h
> @@ -34,6 +34,7 @@ struct voltagedomain;
>   * @cmd_ret_shift: RET field shift in PRM_VC_CMD_VAL_* register
>   * @cmd_off_shift: OFF field shift in PRM_VC_CMD_VAL_* register
>   * @i2c_cfg_reg: I2C configuration register offset
> + * @i2c_cfg_clear_mask: high-speed mode bit clear mask in I2C config register
>   * @i2c_cfg_hsen_mask: high-speed mode bit field mask in I2C config register
>   * @i2c_mcode_mask: MCODE field mask for I2C config register
>   *
> @@ -52,6 +53,7 @@ struct omap_vc_common {
>  	u8 cmd_ret_shift;
>  	u8 cmd_off_shift;
>  	u8 i2c_cfg_reg;
> +	u8 i2c_cfg_clear_mask;
>  	u8 i2c_cfg_hsen_mask;
>  	u8 i2c_mcode_mask;
>  };
> --- a/arch/arm/mach-omap2/vc3xxx_data.c
> +++ b/arch/arm/mach-omap2/vc3xxx_data.c
> @@ -40,6 +40,7 @@ static struct omap_vc_common omap3_vc_common = {
>  	.cmd_onlp_shift	 = OMAP3430_VC_CMD_ONLP_SHIFT,
>  	.cmd_ret_shift	 = OMAP3430_VC_CMD_RET_SHIFT,
>  	.cmd_off_shift	 = OMAP3430_VC_CMD_OFF_SHIFT,
> +	.i2c_cfg_clear_mask = OMAP3430_SREN_MASK,

I know that the prminst rmw current code does:
v &= ~mask;
v |= bits;
and not
v &= ~mask;
v |= (bits & mask);
but to maintain legacy behavior in case the PRCM cleanup sequences
change anything..

	.i2c_cfg_clear_mask = OMAP3430_SREN_MASK | OMAP3430_HSEN_MASK,
?
or
		voltdm->rmw(vc->common->i2c_cfg_clear_mask |
  			    vc->common->i2c_cfg_hsen_mask,
  			    vc->common->i2c_cfg_hsen_mask,
  			    vc->common->i2c_cfg_reg);

no strong feelings though...

>  	.i2c_cfg_hsen_mask = OMAP3430_HSEN_MASK,
>  	.i2c_cfg_reg	 = OMAP3_PRM_VC_I2C_CFG_OFFSET,
>  	.i2c_mcode_mask	 = OMAP3430_MCODE_MASK,
> --- a/arch/arm/mach-omap2/vc44xx_data.c
> +++ b/arch/arm/mach-omap2/vc44xx_data.c
> @@ -42,6 +42,7 @@ static const struct omap_vc_common omap4_vc_common = {
>  	.cmd_ret_shift = OMAP4430_RET_SHIFT,
>  	.cmd_off_shift = OMAP4430_OFF_SHIFT,
>  	.i2c_cfg_reg = OMAP4_PRM_VC_CFG_I2C_MODE_OFFSET,
> +	.i2c_cfg_clear_mask = OMAP4430_SRMODEEN_MASK,
>  	.i2c_cfg_hsen_mask = OMAP4430_HSMODEEN_MASK,
>  	.i2c_mcode_mask	 = OMAP4430_HSMCODE_MASK,
>  };
> 

otherwise, please feel to add:
Reviewed-by: Nishanth Menon <[email-masked]>

-- 
Regards,
Nishanth Menon