Re: [PATCH] iio: adc: qcom-spmi-adc5: Initialize prescale properly
From: Evan Green
Date: Wed Dec 12 2018 - 15:16:20 EST
On Wed, Dec 12, 2018 at 10:41 AM Jonathan Cameron
<jic23@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Sat, 8 Dec 2018 12:05:15 +0000
> Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> > On Tue, 4 Dec 2018 11:57:32 -0800
> > Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote:
> >
> > > On Tue, Dec 04, 2018 at 11:14:19AM -0800, Evan Green wrote:
> > > > adc5_get_dt_data uses a local, prop, feeds it to adc5_get_dt_channel_data,
> > > > and then puts the result into adc->chan_props. The problem is
> > > > adc5_get_dt_channel_data may not initialize that structure fully, so a
> > > > garbage value is used for prescale if the optional "qcom,pre-scaling" is
> > > > not defined in DT. adc5_read_raw then uses this as an array index,
> > > > generating a crash that looks like this:
> > > >
> > > > [ 6.683186] Unable to handle kernel paging request at virtual address ffffff90e78c7964
> > > > Call trace:
> > > > qcom_vadc_scale_code_voltage_factor+0x74/0x104
> > > > qcom_vadc_scale_hw_calib_die_temp+0x20/0x60
> > > > qcom_adc5_hw_scale+0x78/0xa4
> > > > adc5_read_raw+0x3d0/0x65c
> > > > iio_channel_read+0x240/0x30c
> > > > iio_read_channel_processed+0x10c/0x150
> > > > qpnp_tm_get_temp+0xc0/0x40c
> > > > of_thermal_get_temp+0x7c/0x98
> > > > thermal_zone_get_temp+0xac/0xd8
> > > > thermal_zone_device_update+0xc0/0x38c
> > > > qpnp_tm_probe+0x624/0x81c
> > > > platform_drv_probe+0xe4/0x11c
> > > > really_probe+0x188/0x3fc
> > > > driver_probe_device+0xb8/0x188
> > > > __device_attach_driver+0x114/0x180
> > > > bus_for_each_drv+0xd8/0x118
> > > > __device_attach+0x180/0x27c
> > > > device_initial_probe+0x20/0x2c
> > > > bus_probe_device+0x78/0x124
> > > > deferred_probe_work_func+0xfc/0x138
> > > > process_one_work+0x3d8/0x8b0
> > > > process_scheduled_works+0x48/0x6c
> > > > worker_thread+0x488/0x7cc
> > > > kthread+0x24c/0x264
> > > > ret_from_fork+0x10/0x18
> > > >
> > > > Unfortunately, when I went to add the initializer for this and tried to
> > > > boot it, my machine shut down immediately, complaining that it was
> > > > hotter than the sun. It appears that adc5_chans_pmic and adc5_chans_rev2
> > > > were initializing prescale_index as if it were directly a divisor,
> > > > rather than the index into adc5_prescale_ratios that it is.
> > > >
> > > > Fix the uninitialized value, and change the static initialization to use
> > > > indices into adc5_prescale_ratios.
> > > >
> > > > Signed-off-by: Evan Green <evgreen@xxxxxxxxxxxx>
> > > > ---
> > > >
> > > > drivers/iio/adc/qcom-spmi-adc5.c | 58 +++++++++++++++++---------------
> > > > 1 file changed, 31 insertions(+), 27 deletions(-)
> > > >
> > > > diff --git a/drivers/iio/adc/qcom-spmi-adc5.c b/drivers/iio/adc/qcom-spmi-adc5.c
> > > > index f9af6b082916b..6a866cc187f7d 100644
> > > > --- a/drivers/iio/adc/qcom-spmi-adc5.c
> > > > +++ b/drivers/iio/adc/qcom-spmi-adc5.c
> > > > @@ -423,6 +423,7 @@ struct adc5_channels {
> > > > enum vadc_scale_fn_type scale_fn_type;
> > > > };
> > > >
> > > > +/* In these definitions, _pre refers to an index into adc5_prescale_ratios. */
> > > > #define ADC5_CHAN(_dname, _type, _mask, _pre, _scale) \
> > > > { \
> > > > .datasheet_name = _dname, \
> > > > @@ -443,63 +444,63 @@ struct adc5_channels {
> > > > _pre, _scale) \
> > > >
> > > > static const struct adc5_channels adc5_chans_pmic[ADC5_MAX_CHANNEL] = {
> > > > - [ADC5_REF_GND] = ADC5_CHAN_VOLT("ref_gnd", 1,
> > > > + [ADC5_REF_GND] = ADC5_CHAN_VOLT("ref_gnd", 0,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_1P25VREF] = ADC5_CHAN_VOLT("vref_1p25", 1,
> > > > + [ADC5_1P25VREF] = ADC5_CHAN_VOLT("vref_1p25", 0,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_VPH_PWR] = ADC5_CHAN_VOLT("vph_pwr", 3,
> > > > + [ADC5_VPH_PWR] = ADC5_CHAN_VOLT("vph_pwr", 1,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_VBAT_SNS] = ADC5_CHAN_VOLT("vbat_sns", 3,
> > > > + [ADC5_VBAT_SNS] = ADC5_CHAN_VOLT("vbat_sns", 1,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_DIE_TEMP] = ADC5_CHAN_TEMP("die_temp", 1,
> > > > + [ADC5_DIE_TEMP] = ADC5_CHAN_TEMP("die_temp", 0,
> > > > SCALE_HW_CALIB_PMIC_THERM)
> > > > - [ADC5_USB_IN_I] = ADC5_CHAN_VOLT("usb_in_i_uv", 1,
> > > > + [ADC5_USB_IN_I] = ADC5_CHAN_VOLT("usb_in_i_uv", 0,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_USB_IN_V_16] = ADC5_CHAN_VOLT("usb_in_v_div_16", 16,
> > > > + [ADC5_USB_IN_V_16] = ADC5_CHAN_VOLT("usb_in_v_div_16", 8,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_CHG_TEMP] = ADC5_CHAN_TEMP("chg_temp", 1,
> > > > + [ADC5_CHG_TEMP] = ADC5_CHAN_TEMP("chg_temp", 0,
> > > > SCALE_HW_CALIB_PM5_CHG_TEMP)
> > > > /* Charger prescales SBUx and MID_CHG to fit within 1.8V upper unit */
> > > > - [ADC5_SBUx] = ADC5_CHAN_VOLT("chg_sbux", 3,
> > > > + [ADC5_SBUx] = ADC5_CHAN_VOLT("chg_sbux", 1,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_MID_CHG_DIV6] = ADC5_CHAN_VOLT("chg_mid_chg", 6,
> > > > + [ADC5_MID_CHG_DIV6] = ADC5_CHAN_VOLT("chg_mid_chg", 3,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_XO_THERM_100K_PU] = ADC5_CHAN_TEMP("xo_therm", 1,
> > > > + [ADC5_XO_THERM_100K_PU] = ADC5_CHAN_TEMP("xo_therm", 0,
> > > > SCALE_HW_CALIB_XOTHERM)
> > > > - [ADC5_AMUX_THM1_100K_PU] = ADC5_CHAN_TEMP("amux_thm1_100k_pu", 1,
> > > > + [ADC5_AMUX_THM1_100K_PU] = ADC5_CHAN_TEMP("amux_thm1_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM2_100K_PU] = ADC5_CHAN_TEMP("amux_thm2_100k_pu", 1,
> > > > + [ADC5_AMUX_THM2_100K_PU] = ADC5_CHAN_TEMP("amux_thm2_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM3_100K_PU] = ADC5_CHAN_TEMP("amux_thm3_100k_pu", 1,
> > > > + [ADC5_AMUX_THM3_100K_PU] = ADC5_CHAN_TEMP("amux_thm3_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM2] = ADC5_CHAN_TEMP("amux_thm2", 1,
> > > > + [ADC5_AMUX_THM2] = ADC5_CHAN_TEMP("amux_thm2", 0,
> > > > SCALE_HW_CALIB_PM5_SMB_TEMP)
> > > > };
> > > >
> > > > static const struct adc5_channels adc5_chans_rev2[ADC5_MAX_CHANNEL] = {
> > > > - [ADC5_REF_GND] = ADC5_CHAN_VOLT("ref_gnd", 1,
> > > > + [ADC5_REF_GND] = ADC5_CHAN_VOLT("ref_gnd", 0,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_1P25VREF] = ADC5_CHAN_VOLT("vref_1p25", 1,
> > > > + [ADC5_1P25VREF] = ADC5_CHAN_VOLT("vref_1p25", 0,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_VPH_PWR] = ADC5_CHAN_VOLT("vph_pwr", 3,
> > > > + [ADC5_VPH_PWR] = ADC5_CHAN_VOLT("vph_pwr", 1,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_VBAT_SNS] = ADC5_CHAN_VOLT("vbat_sns", 3,
> > > > + [ADC5_VBAT_SNS] = ADC5_CHAN_VOLT("vbat_sns", 1,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_VCOIN] = ADC5_CHAN_VOLT("vcoin", 3,
> > > > + [ADC5_VCOIN] = ADC5_CHAN_VOLT("vcoin", 1,
> > > > SCALE_HW_CALIB_DEFAULT)
> > > > - [ADC5_DIE_TEMP] = ADC5_CHAN_TEMP("die_temp", 1,
> > > > + [ADC5_DIE_TEMP] = ADC5_CHAN_TEMP("die_temp", 0,
> > > > SCALE_HW_CALIB_PMIC_THERM)
> > > > - [ADC5_AMUX_THM1_100K_PU] = ADC5_CHAN_TEMP("amux_thm1_100k_pu", 1,
> > > > + [ADC5_AMUX_THM1_100K_PU] = ADC5_CHAN_TEMP("amux_thm1_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM2_100K_PU] = ADC5_CHAN_TEMP("amux_thm2_100k_pu", 1,
> > > > + [ADC5_AMUX_THM2_100K_PU] = ADC5_CHAN_TEMP("amux_thm2_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM3_100K_PU] = ADC5_CHAN_TEMP("amux_thm3_100k_pu", 1,
> > > > + [ADC5_AMUX_THM3_100K_PU] = ADC5_CHAN_TEMP("amux_thm3_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM4_100K_PU] = ADC5_CHAN_TEMP("amux_thm4_100k_pu", 1,
> > > > + [ADC5_AMUX_THM4_100K_PU] = ADC5_CHAN_TEMP("amux_thm4_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_AMUX_THM5_100K_PU] = ADC5_CHAN_TEMP("amux_thm5_100k_pu", 1,
> > > > + [ADC5_AMUX_THM5_100K_PU] = ADC5_CHAN_TEMP("amux_thm5_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > - [ADC5_XO_THERM_100K_PU] = ADC5_CHAN_TEMP("xo_therm_100k_pu", 1,
> > > > + [ADC5_XO_THERM_100K_PU] = ADC5_CHAN_TEMP("xo_therm_100k_pu", 0,
> > > > SCALE_HW_CALIB_THERM_100K_PULLUP)
> > > > };
> > > >
> > > > @@ -558,6 +559,9 @@ static int adc5_get_dt_channel_data(struct adc5_chip *adc,
> > > > return ret;
> > > > }
> > > > prop->prescale = ret;
> > > > + } else {
> > > > + prop->prescale =
> > > > + adc->data->adc_chans[prop->channel].prescale_index;
> > > > }
> > > >
> > > > ret = of_property_read_u32(node, "qcom,hw-settle-time", &value);
> > >
> > > Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> > >
> > > Good as an immediate fix.
> > >
> > > In the long term I wonder if it would be better to pass a ratio to
> > > ADC5_CHAN_XYZ and store it in struct adc5_channel_prop, instead of
> > > specifying the index, which is more error prone and errors are harder
> > > to spot. With this adc5_prescale_ratios would still exist, but only be
> > > used for the sanity check of prescaling values from the DT.
> >
> > I am going to let this sit for a little longer to let Siddartha have
> > a chance to comment as well. We are getting late this cycle
> > so this may end up going upstream at the start of the next one
> > (as it'll be marked for stable that shouldn't matter much).
> >
> > Poke me if I seem to have forgotten it in a week or so.
> I've applied this to the togreg branch of iio.git so it'll go in
> during the next merge window (hopefully). Marked for stable.
>
Thanks, Jonathan!