On Wed, Aug 02, 2023 at 09:27:17AM +0200, Hans Verkuil wrote: > Hmm, this is old code and when digging into this I noticed inconsistencies > in how it is used and how it is documented. > > It's used by the v4l2_subdev interrupt_service_routine callback. The header > include/media/v4l2-subdev.h claims that it is called from IRQ context, but this > isn't true in most cases. It's used primarily to pass on interrupts meant for > i2c video receivers/transmitters that arrive at the bridge chip to the actual > i2c device. And that happens in work handlers that allow the use of locking. > > I found one exception where it is also used for an IR (infrared) receiver and > there it is actually called from IRQ context. It doesn't use i2c or sleeps/locking > in that case, so it is safe. > > But what confuses me is that you state 'This looks at functions which are passed to > request_irq()', but adv7511_isr isn't passed to request_irq. So why is this warning > raised? > Actually you're right. I was thrown off a bit by the name. Was the exception cx23885_irq()? Because that's what Smatch is concerned about. That calls "v4l2_subdev_call(dev->sd_ir, core, interrupt_service_routine," and Smatch thinks interrupt_service_routine can point to here. Thanks for looking at this. It's a new check I'm working on and it still has a bunch of issues. regards, dan carpenter
