linux-kernel - Re: Tegra boots failing due to as3722 I/O errors

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Date:	Wed, 30 Mar 2016 12:31:47 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Mark Brown <broonie@...nel.org>,
	Laxman Dewangan <ldewangan@...dia.com>,
	"Maciej S. Szmigiero" <mail@...iej.szmigiero.name>,
	Lee Jones <lee.jones@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>,
	"Thierry Reding" <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>
CC:	<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	"Liam Girdwood" <lgirdwood@...il.com>
Subject: Re: Tegra boots failing due to as3722 I/O errors

Hi Mark,

On 29/03/16 20:03, Mark Brown wrote:
> * PGP Signed by an unknown key
> 
> Hi,
> 
> Currently the Jetson TK1 is failing to get regulators for MMC with at
> least my regulator tree and probably -next also due to:
> 
> [    1.665750] as3722 4-0040: AS3722 with revision 0x1 found
> [    1.682945] +VDDIO_SDMMC3: failed to get the current voltage(-22)
> [    1.689135] as3722-regulator as3722-regulator: regulator 13 register failed -22
> [    1.697593] as3722-regulator: probe of as3722-regulator failed with error -22
> 
> The get voltage operation here is just a simple mapping of a bitfield in
> the regmap which suggests that the underlying problem is somewhere
> further down the stack like the MFD or I2C drivers.  The error is
> -EINVAL which suggests something like the register not being marked as
> readable but the _VOLTAGE_REG registers appear to be marked as readable
> in the MFD.
> 
> Full log for one boot at:
> 
>   https://storage.kernelci.org/broonie-regulator/v4.6-rc1-24-ga7e614dd1f91/arm-multi_v7_defconfig+CONFIG_SMP=n/lab-mhart/boot-tegra124-jetson-tk1.html

Thanks for the report. I took a quick look at this and it turns out
that i2c and regmap are all working fine. The problem is the
VDDIO_SDMMC3 LDO (aka. LDO6) on the as3722 has a bypass mode which is
not represented by the voltage ranges for the LDO. On boot the LDO is
in bypass and returns a value which is not recognised and hence an
EINVAL is returned. The following change fixes the problem. The 0x3F
value represents the bypass mode. I will send out a formal patch.

Cheers
Jon

diff --git a/drivers/regulator/as3722-regulator.c b/drivers/regulator/as3722-regulator.c
index 8b046ee..f16d0e5 100644
--- a/drivers/regulator/as3722-regulator.c
+++ b/drivers/regulator/as3722-regulator.c
@@ -438,6 +438,13 @@ static const struct regulator_linear_range as3722_ldo_ranges[] = {
        REGULATOR_LINEAR_RANGE(1725000, 0x40, 0x7F, 25000),
 };
 
+static const struct regulator_linear_range as3722_ldo6_ranges[] = {
+       REGULATOR_LINEAR_RANGE(0, 0x00, 0x00, 0),
+       REGULATOR_LINEAR_RANGE(825000, 0x01, 0x24, 25000),
+       REGULATOR_LINEAR_RANGE(3300000, 0x3F, 0x3F, 0),
+       REGULATOR_LINEAR_RANGE(1725000, 0x40, 0x7F, 25000),
+};
+
 static struct regulator_ops as3722_ldo_ops = {
        .is_enabled = regulator_is_enabled_regmap,
        .enable = regulator_enable_regmap,
@@ -863,6 +870,16 @@ static int as3722_regulator_probe(struct platform_device *pdev)
                        as3722_regs->desc[id].n_linear_ranges =
                                        ARRAY_SIZE(as3722_sd2345_ranges);
                        break;
+               case AS3722_REGULATOR_ID_LDO6:
+                       if (reg_config->ext_control)
+                               ops = &as3722_ldo_extcntrl_ops;
+                       else
+                               ops = &as3722_ldo_ops;
+                       as3722_regs->desc[id].enable_time = 500;
+                       as3722_regs->desc[id].linear_ranges = as3722_ldo6_ranges;
+                       as3722_regs->desc[id].n_linear_ranges =
+                                               ARRAY_SIZE(as3722_ldo6_ranges);
+                       break;
                default:
                        if (reg_config->ext_control)
                                ops = &as3722_ldo_extcntrl_ops;