diff mbox series

[v4,1/1] iio: mtk-auxadc: fix case IIO_CHAN_INFO_PROCESSED

Message ID 20210926073028.11045-2-hui.liu@mediatek.com (mailing list archive)
State Accepted
Headers show
Series AUXADC: Mediatek auxadc driver | expand

Commit Message

Hui Liu Sept. 26, 2021, 7:30 a.m. UTC 
From: Hui Liu <hui.liu@mediatek.com>

The previous driver does't apply the necessary scaling to take the
voltage range into account.
We change readback value from raw data to input voltage to fix case
IIO_CHAN_INFO_PROCESSED.

Fixes: ace4cdfe67be ("iio: adc: mt2701: Add Mediatek auxadc driver for mt2701.")
Signed-off-by: Hui Liu <hui.liu@mediatek.com>
---
 drivers/iio/adc/mt6577_auxadc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Hsin-Yi Wang Oct. 31, 2021, 4:49 p.m. UTC | #1 
On Sun, Sep 26, 2021 at 7:26 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sun, 26 Sep 2021 15:30:28 +0800
> Hui-Liu Liu <hui.liu@mediatek.com> wrote:
>
> > From: Hui Liu <hui.liu@mediatek.com>
> >
> > The previous driver does't apply the necessary scaling to take the
> > voltage range into account.
> > We change readback value from raw data to input voltage to fix case
> > IIO_CHAN_INFO_PROCESSED.
> >
> > Fixes: ace4cdfe67be ("iio: adc: mt2701: Add Mediatek auxadc driver for mt2701.")
> > Signed-off-by: Hui Liu <hui.liu@mediatek.com>
>
Hi Hui Liu,

After this patch, mt8183 tboard thermal sensor[1] is getting incorrect value:
Before the patch:
/sys/class/thermal/thermal_zone0/temp:41488 (cpu)
/sys/class/thermal/thermal_zone7/temp:35433 (tboard)
/sys/class/thermal/thermal_zone8/temp:33709 (tboard)

After the patch:
/sys/class/thermal/thermal_zone0/temp:40365 (cpu)
/sys/class/thermal/thermal_zone7/temp:69781 (tboard)
/sys/class/thermal/thermal_zone8/temp:69014 (tboard)

[1] https://elixir.bootlin.com/linux/v5.15-rc7/source/arch/arm64/boot/dts/mediatek/mt8183-kukui.dtsi#L862

>
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> Linux-mediatek mailing list
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> http://lists.infradead.org/mailman/listinfo/linux-mediatek
diff mbox series

Patch

diff --git a/drivers/iio/adc/mt6577_auxadc.c b/drivers/iio/adc/mt6577_auxadc.c
index 79c1dd68b909..d4fccd52ef08 100644
--- a/drivers/iio/adc/mt6577_auxadc.c
+++ b/drivers/iio/adc/mt6577_auxadc.c
@@ -82,6 +82,10 @@  static const struct iio_chan_spec mt6577_auxadc_iio_channels[] = {
 	MT6577_AUXADC_CHANNEL(15),
 };
 
+/* For Voltage calculation */
+#define VOLTAGE_FULL_RANGE  1500	/* VA voltage */
+#define AUXADC_PRECISE      4096	/* 12 bits */
+
 static int mt_auxadc_get_cali_data(int rawdata, bool enable_cali)
 {
 	return rawdata;
@@ -191,6 +195,10 @@  static int mt6577_auxadc_read_raw(struct iio_dev *indio_dev,
 		}
 		if (adc_dev->dev_comp->sample_data_cali)
 			*val = mt_auxadc_get_cali_data(*val, true);
+
+		/* Convert adc raw data to voltage: 0 - 1500 mV */
+		*val = *val * VOLTAGE_FULL_RANGE / AUXADC_PRECISE;
+
 		return IIO_VAL_INT;
 
 	default: