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From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: Md Shofiqul Islam <shofiqtest@gmail.com>
Cc: jic23@kernel.org, lars@metafoo.de, Michael.Hennerich@analog.com,
	dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org,
	linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] iio: accel: adxl3xx: Add timestamps to FIFO data
Date: Sun, 10 May 2026 15:58:16 +0300	[thread overview]
Message-ID: <agCA6HUnN5KMXj8J@ashevche-desk.local> (raw)
In-Reply-To: <20260510082556.3867-1-shofiqtest@gmail.com>

On Sun, May 10, 2026 at 11:25:51AM +0300, Md Shofiqul Islam wrote:
> Five ADXL-family accelerometer drivers (ADXL313, ADXL345, ADXL367,
> ADXL372, ADXL380) push buffered samples using iio_push_to_buffers(),
> which does not attach a hardware timestamp to the scan data.
> Userspace consumers therefore receive samples with no timing
> information.
> 
> This series adds timestamp support uniformly across the family:
> 
>   - A scan buffer struct with an aligned_s64 ts field is added to each
>     driver's state struct.  The struct layout ensures the timestamp
>     field sits at an 8-byte aligned offset as required by
>     iio_push_to_buffers_with_timestamp().
> 
>   - In the FIFO push loop, FIFO data is copied into scan.channels via
>     memcpy(), then iio_push_to_buffers_with_timestamp() is called with
>     a single timestamp captured once per interrupt with
>     iio_get_time_ns().  Using one timestamp per IRQ is consistent with
>     the existing approach in the same handlers for event timestamps.
> 
>   - For ADXL367, the helper adxl367_push_fifo_data() gains a s64 ts
>     parameter so the timestamp captured in the IRQ handler is passed
>     through instead of calling iio_get_time_ns() a second time.
> 
>   - For ADXL372 and ADXL380, where the IRQ handler already called
>     iio_get_time_ns() for the event push, the same captured timestamp
>     is now also passed to the FIFO push, removing the duplicate call.
> 
> The ADXL313 and ADXL345 drivers always scan all three axes together
> (available_scan_masks contains only the full X|Y|Z mask), so their
> scan buffer layout is fixed.  The ADXL367, ADXL372, and ADXL380
> drivers support variable scan masks; fifo_set_size tracks the number
> of enabled channels per sample set and is used as the memcpy length.

This is sensitive change. Do we have any confirmation that this
- does work as expected on real HW and platforms that use these devices
- does not break any ABI

-- 
With Best Regards,
Andy Shevchenko



      parent reply	other threads:[~2026-05-10 12:58 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-10  8:25 [PATCH 0/5] iio: accel: adxl3xx: Add timestamps to FIFO data Md Shofiqul Islam
2026-05-10  8:25 ` [PATCH 1/5] iio: accel: adxl372: Add timestamp " Md Shofiqul Islam
2026-05-10  8:25 ` [PATCH 2/5] iio: accel: adxl380: " Md Shofiqul Islam
2026-05-10  8:25 ` [PATCH 3/5] iio: accel: adxl367: " Md Shofiqul Islam
2026-05-10  8:25 ` [PATCH 4/5] iio: accel: adxl313: " Md Shofiqul Islam
2026-05-10  8:25 ` [PATCH 5/5] iio: accel: adxl345: " Md Shofiqul Islam
2026-05-10 12:58 ` Andy Shevchenko [this message]

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