Re: [PATCH 1/3] soundwire: allow drivers to check whether the peripheral is present

[Cezary Rojewski]

On 9/15/2026 3:13 PM, Bard Liao wrote:
> A ghost peripheral may be listed in the ACPI table and we want to skip
> it. Add enumeration_complete and is_present in struct sdw_bus{} allow
> the driver to wait and check whether a peripheral is present.
> 
> Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
> Reviewed-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/soundwire/bus.c       | 7 +++++++
>  include/linux/soundwire/sdw.h | 5 +++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> index aeaae5a57c89..b49864ca683a 100644
> --- a/drivers/soundwire/bus.c
> +++ b/drivers/soundwire/bus.c
> @@ -161,7 +161,13 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
>  	bus->params.curr_dr_freq = bus->params.max_dr_freq;
>  	bus->params.curr_bank = SDW_BANK0;
>  	bus->params.next_bank = SDW_BANK1;
> +	/*
> +	 * Set is_present = true by default. It will be set to false when no peripherals
> +	 * are attached on the bus.
> +	 */
> +	bus->is_present = true;

Does the approach permit existence of non-ghost, SDW master instance
with no codecs attached?

> +	init_completion(&bus->enumeration_complete);
>  	return 0;
>  }