Re: [PATCH v2 1/4] firmware: cs_dsp: Add API to hibernate the DSP

[Richard Fitzgerald]

On 24/02/2026 4:18 pm, Stefan Binding wrote:
> For some parts, the DSP is kept running when in low power mode
> (hibernation), leaving the firmware ALSA controls enabled, but the
> registers are inaccessible. Attempts to access volatile firmware
> controls whilst in this state would produce errors in the kernel log
> due to a regmap_raw_read() into DSP registers whilst the regmap is in
> cache_only.
>
> To remove this error log, add a hibernating flag to indicate that the
> controls are inaccessible, so we no longer try to read or write to the
> registers whilst the regmap is in cache_only.
>
> This would still produce an error when trying to read or write to these
> controls, but this would be a different error (-EPERM instead of
> -EBUSY), and would not produce a spurious error log in the kernel.
>
> Upon wake from hibernation, the control caches are re-synced to the
> hardware, if the DSP is running.
>
> Signed-off-by: Stefan Binding <sbinding@xxxxxxxxxxxxxxxxxxxxx>
> ---
>   drivers/firmware/cirrus/cs_dsp.c       | 49 +++++++++++++++++++++++---
>   include/linux/firmware/cirrus/cs_dsp.h |  3 ++
>   2 files changed, 48 insertions(+), 4 deletions(-)

Reviewed-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>