Re: [PATCH 02/15] ASoC: SDCA: Add manual PM runtime gets to IRQ handlers

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

On Mon, Sep 08, 2025 at 01:42:40PM +0200, Pierre-Louis Bossart wrote:
> On 9/5/25 16:31, Charles Keepax wrote:
> > @@ -86,18 +88,25 @@ static irqreturn_t function_status_handler(int irq, void *data)
> >  {
> >  	struct sdca_interrupt *interrupt = data;
> >  	struct device *dev = interrupt->component->dev;
> > +	irqreturn_t irqret = IRQ_NONE;
> >  	unsigned int reg, val;
> >  	unsigned long status;
> >  	unsigned int mask;
> >  	int ret;
> >  
> > +	ret = pm_runtime_get_sync(dev);
> 
> what does 'dev' represent? The SDCA function device or the
> parent SoundWire peripheral device?

SDCA function device here.

> I would think it's the former, with the parent-child
> relationship used by the runtime_pm framework to resume the
> parent peripheral device if needed.

Yes this would cause the parent to power up, but there is
nuance here. The parent has actually already been powered up
by regmap IRQ. The thing here is SDCA is weird, the interrupts
are defined at the device level, but all the handling is at the
function level.

To some extent this is also a consequence of having a regmap per
function. Regmap IRQ is registered against the SoundWire device,
as it needs to access the device level IRQ registers. But the
handlers are per function and need to make sure an individual
functions register map is out of cache_only so need to do a
runtime get on the function specifically. In the past with
multi-function codecs we have been able to cheat a little here
as resuming the parent actually did everything necessary to
communicate with a part of the device.

> maybe use sdev and pdev as an arbitrary convention to help the reader?
> 

I quite like the idea of this as a naming convention, will have
a look at updating stuff.

Thanks,
Charles