[U-Boot] [PATCH v2] i.MX28: Check if we are using a valid VBUS for power initialization

[Marek Vasut]

Dear Otavio Salvador,

> Signed-off-by: Otavio Salvador <otavio at ossystems.com.br>
> ---
> Changes in v2:
> - add comments
> - fix when we have vbus OR vdd5v
> - improve patch short description
> 
>  arch/arm/cpu/arm926ejs/mx28/spl_power_init.c |   26
> +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7
> deletions(-)
> 
> diff --git a/arch/arm/cpu/arm926ejs/mx28/spl_power_init.c
> b/arch/arm/cpu/arm926ejs/mx28/spl_power_init.c index 4b09b0c..fdf810c
> 100644
> --- a/arch/arm/cpu/arm926ejs/mx28/spl_power_init.c
> +++ b/arch/arm/cpu/arm926ejs/mx28/spl_power_init.c
> @@ -564,6 +564,15 @@ void mx28_batt_boot(void)
>  		0x8 << POWER_5VCTRL_CHARGE_4P2_ILIMIT_OFFSET);
>  }
> 
> +static int mx28_valid_vbus(void)
> +{
> +	struct mx28_power_regs *power_regs =
> +		(struct mx28_power_regs *)MXS_POWER_BASE;
> +
> +	/* iMX23 uses POWER_STS_VBUSVALID_STATUS at same offset */
> +	return readl(&power_regs->hw_power_sts) & POWER_STS_VBUSVALID0_STATUS;
> +}
> +
>  void mx28_handle_5v_conflict(void)
>  {
>  	struct mx28_power_regs *power_regs =
> @@ -577,14 +586,19 @@ void mx28_handle_5v_conflict(void)
>  		tmp = readl(&power_regs->hw_power_sts);
> 
>  		if (tmp & POWER_STS_VDDIO_BO) {
> +			/*
> +			 * VDDIO has a brownout, then the VDD5V_GT_VDDIO becomes
> +			 * unreliable
> +			 */
>  			mx28_powerdown();
>  			break;
>  		}
> 
> -		if (tmp & POWER_STS_VDD5V_GT_VDDIO) {
> +		if (mx28_valid_vbus() || (tmp & POWER_STS_VDD5V_GT_VDDIO)) {
>  			mx28_boot_valid_5v();
>  			break;
>  		} else {
> +			/* Neither 5v sees 5v so we power down */
>  			mx28_powerdown();
>  			break;
>  		}
> @@ -601,17 +615,15 @@ void mx28_5v_boot(void)
>  	struct mx28_power_regs *power_regs =
>  		(struct mx28_power_regs *)MXS_POWER_BASE;
> 
> -	/*
> -	 * NOTE: In original IMX-Bootlets, this also checks for VBUSVALID,
> -	 * but their implementation always returns 1 so we omit it here.
> -	 */
> -	if (readl(&power_regs->hw_power_sts) & POWER_STS_VDD5V_GT_VDDIO) {
> +	if (mx28_valid_vbus() &&
> +		(readl(&power_regs->hw_power_sts) & POWER_STS_VDD5V_GT_VDDIO)) {
>  		mx28_boot_valid_5v();
>  		return;
>  	}
> 
>  	early_delay(1000);
> -	if (readl(&power_regs->hw_power_sts) & POWER_STS_VDD5V_GT_VDDIO) {
> +	if (mx28_valid_vbus() &&

This is still likely to break any device that doesn't source it's 5V power 
supply from USB

> +		(readl(&power_regs->hw_power_sts) & POWER_STS_VDD5V_GT_VDDIO)) {
>  		mx28_boot_valid_5v();
>  		return;
>  	}

Best regards,
Marek Vasut