Re: [PATCH V3 10/10] soundwire: amd: fix IRQ thread dropping STATUS_0TO7 on simultaneous wake

[Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>]

On 10/13/26 10:49, Vijendar Mukunda wrote:
> When the wake bit and a device-state change arrive at the same time,
> the IRQ thread returned early after handling wake, silently discarding
> STATUS_0TO7. If the manager is already at D0, pm_request_resume() is
> a no-op so the dropped ATTACHED event is never recovered and jack
> detection stops working.

this wording is very very hard to follow. Please consider rewording to
describe the race condition in better ways...

> Remove the early return on wake: call amd_sdw_process_wake_event(),
> strip the wake bit from the local STATUS_8TO11 copy, and continue to
> the normal slave-status processing path. Remove the STATUS_8TO11 clear
> from amd_sdw_process_wake_event() so the single tail clear in
> amd_sdw_irq_thread() is the only write to the register per invocation,
> eliminating the double-clear race where a new event arriving between
> two successive clears would be wiped before being read.
> 
> Fixes: 66c878838f37 ("soundwire: amd: handle SoundWire wake enable interrupt")
> Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@amd.com>
> ---
>  drivers/soundwire/amd_manager.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/soundwire/amd_manager.c b/drivers/soundwire/amd_manager.c
> index 1a252a81269a..beb982b17fa9 100644
> --- a/drivers/soundwire/amd_manager.c
> +++ b/drivers/soundwire/amd_manager.c
> @@ -1006,7 +1006,6 @@ static void amd_sdw_process_wake_event(struct amd_sdw_manager *amd_manager)
>  	dev_dbg(amd_manager->dev, "SoundWire Wake event reported\n");
>  	pm_request_resume(amd_manager->dev);

... specifically why this would be a no-op and ...

>  	writel(0x00, amd_manager->acp_mmio + ACP_SW_WAKE_EN(amd_manager->instance));
> -	writel(0x00, amd_manager->mmio + ACP_SW_STATE_CHANGE_STATUS_8TO11);
>  }
>  
>  static void amd_sdw_irq_thread(struct work_struct *work)
> @@ -1023,8 +1022,11 @@ static void amd_sdw_irq_thread(struct work_struct *work)
>  
>  	dev_dbg(amd_manager->dev, "[SDW%d] SDW INT: 0to7=0x%x, 8to11=0x%x\n",
>  		amd_manager->instance, status_change_0to7, status_change_8to11);
> -	if (status_change_8to11 & AMD_SDW_WAKE_STAT_MASK)
> -		return amd_sdw_process_wake_event(amd_manager);
> +
> +	if (status_change_8to11 & AMD_SDW_WAKE_STAT_MASK) {
> +		amd_sdw_process_wake_event(amd_manager);
> +		status_change_8to11 &= ~AMD_SDW_WAKE_STAT_MASK;

... why adding this mask solves the race
> +	}
>  
>  	if (status_change_8to11 & AMD_SDW_PREQ_INTR_STAT) {
>  		amd_sdw_read_and_process_ping_status(amd_manager);