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

[Pierre-Louis Bossart]

On 9/15/26 19:32, Cezary Rojewski wrote:
> 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?

Also wondering how the 'mockup' codecs would be handled? That's very
useful to test a manager with no actual codecs attached.
> 
>> +	init_completion(&bus->enumeration_complete);
>>  	return 0;
>>  }