Re: [PATCH v5 0/3] ALSA: compress_offload: Add 64-bit safe timestamp API

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Fri, Sep 05, 2025 at 10:12:53AM +0100, Joris Verhaegen wrote:
> The current compress offload timestamping API relies on struct
> snd_compr_tstamp, whose cumulative counters like copied_total are
> defined as __u32. On long-running high-resolution audio streams, these
> 32-bit counters can overflow, causing incorrect availability
> calculations.
> 
> This patch series transitions to a 64-bit safe API to solve the problem
> while maintaining perfect backward compatibility with the existing UAPI.
> The pointer operation is reworked to use a new timestamp struct with
> 64-bit fields for the cumulative counters, named snd_compr_tstamp64.
> ASoC drivers are updated to use the 64-bit structures. Corresponding
> ioctls are added to expose them to user-space.
> 
> The series is structured as follows:
> 
> Patch 1: Updates the pointer op, refactors the core logic and ASoC
> drivers to use it, and defines the new UAPI structs.
> 
> Patch 2: Exposes the SNDRV_COMPRESS_TSTAMP64 ioctl.
> 
> Patch 3: Exposes the corresponding SNDRV_COMPRESS_AVAIL64 ioctl.
> 
> This series has been tested on a Pixel 9 device. All compress offload
> use cases, including long-running playback, were verified to work
> correctly with the new 64-bit API.
> 
> Thanks,
> Joris (George) Verhaegen
> 
> Signed-off-by: Joris Verhaegen <verhaegen@google.com>
> 
> ---

Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>

Thanks,
Charles