[PATCH v5 05/14] iio: magnetometer: yas530: Change data type of calibration coefficients

From: Jakob Hauser <jahau@rocketmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>,
	Linus Walleij <linus.walleij@linaro.org>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Hans de Goede <hdegoede@redhat.com>,
	linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
	phone-devel@vger.kernel.org,
	~postmarketos/upstreaming@lists.sr.ht,
	Jakob Hauser <jahau@rocketmail.com>
Subject: [PATCH v5 05/14] iio: magnetometer: yas530: Change data type of calibration coefficients
Date: Mon,  8 Aug 2022 01:02:10 +0200	[thread overview]
Message-ID: <9e95569cf94790b77d82dd29a230716717cef100.1659909060.git.jahau@rocketmail.com> (raw)
In-Reply-To: <cover.1659909060.git.jahau@rocketmail.com>

This is a preparation for adding YAS537 variant.

YAS537 uses other data types on the calibration coefficients [1] than YAS530 [2]
and YAS532 [3].

On YAS537, at least for a4 and a7 this could matter because 8-bit unsigned data
from the register gets stored into a signed data type, therefore this should be
8-bit as well.

For YAS530/532, on the other hand, it doesn't seem to matter. The size of a2-a9
and k is smaller than 8-bit at extraction, also the applied math is low. And
Cx/Cy1/Cy2, now being defined as signed 16-bit, are extracted as unsigned 8-bit
and undergo only minor math.

[1] https://github.com/msm8916-mainline/android_kernel_qcom_msm8916/blob/GT-I9195I/drivers/iio/magnetometer/yas_mag_drv-yas537.c#L76-L78
[2] https://github.com/NovaFusion/android_kernel_samsung_golden/blob/cm-12.1/drivers/sensor/compass/yas_mag_driver-yas530.c#L526-L527
[3] https://github.com/msm8916-mainline/android_kernel_qcom_msm8916/blob/GT-I9195I/drivers/iio/magnetometer/yas_mag_drv-yas532.c#L76-L77

Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/iio/magnetometer/yamaha-yas530.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/magnetometer/yamaha-yas530.c b/drivers/iio/magnetometer/yamaha-yas530.c
index c6889a30a1b5..839baeca673a 100644
--- a/drivers/iio/magnetometer/yamaha-yas530.c
+++ b/drivers/iio/magnetometer/yamaha-yas530.c
@@ -103,9 +103,11 @@ struct yas5xx_calibration {
 	s32 r[3];
 	u32 f[3];
 	/* Temperature compensation calibration */
-	s32 Cx, Cy1, Cy2;
+	s16 Cx, Cy1, Cy2;
 	/* Misc calibration coefficients */
-	s32 a2, a3, a4, a5, a6, a7, a8, a9, k;
+	s8  a2, a3, a4, a6, a7, a8;
+	s16 a5, a9;
+	u8  k;
 	/* clock divider */
 	u8 dck;
 };
-- 
2.35.1

