linux-kernel - Re: [PATCH] iio: imu: st_lsm6dsx: Fix check for invalid samples from FIFO

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Message-ID: <aXDK6KRIIPjJxfFK@smile.fi.intel.com>
Date: Wed, 21 Jan 2026 14:47:36 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Francesco Lavra <flavra@...libre.com>
Cc: Lorenzo Bianconi <lorenzo@...nel.org>,
	Jonathan Cameron <jic23@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: imu: st_lsm6dsx: Fix check for invalid samples from
 FIFO

On Wed, Jan 21, 2026 at 12:27:57PM +0100, Francesco Lavra wrote:
> The DRDY_MASK feature implemented in sensor chips marks gyroscope and
> accelerometer invalid samples (i.e. samples that have been acquired during
> the settling time of sensor filters) with the special values 0x7FFFh,
> 0x7FFE, and 0x7FFD.
> The driver checks FIFO samples against these special values in order to
> discard invalid samples; however, it does the check regardless of the type
> of samples being processed, whereas this feature is specific to gyroscope
> and accelerometer data. This could cause valid samples to be discarded.
> Fix the above check so that it takes into account the type of samples being
> processed.

...

>  st_lsm6dsx_push_tagged_data(struct st_lsm6dsx_hw *hw, u8 tag,
>  			    u8 *data, s64 ts)
>  {
> -	s16 val = le16_to_cpu(*(__le16 *)data);
>  	struct st_lsm6dsx_sensor *sensor;
>  	struct iio_dev *iio_dev;
>  
>  	/* invalid sample during bootstrap phase */
> -	if (val >= ST_LSM6DSX_INVALID_SAMPLE)
> +	if ((tag == ST_LSM6DSX_GYRO_TAG || tag == ST_LSM6DSX_ACC_TAG) &&
> +	    (s16)le16_to_cpup((__le16 *)data) >= ST_LSM6DSX_INVALID_SAMPLE)

Since data is u8 *, it might appear on unaligned addresses and the proper
conversion here is to use get_unaligned_le16() without any of those ugly
castings.

>  		return -EINVAL;

-- 
With Best Regards,
Andy Shevchenko