Re: [PATCH 2/4] media: rkisp1: Fix IRQ handler return values

[Tomi Valkeinen]

On 05/12/2023 13:57, Adam Ford wrote:
> On Tue, Dec 5, 2023 at 2:10 AM Tomi Valkeinen
> <tomi.valkeinen@xxxxxxxxxxxxxxxx> wrote:
> > The IRQ handler rkisp1_isr() calls sub-handlers, all of which returns an
> > irqreturn_t value, but rkisp1_isr() ignores those values and always
> > returns IRQ_HANDLED.
> >
> > Fix this by collecting the return values, and returning IRQ_HANDLED or
> > IRQ_NONE as appropriate.
> >
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c | 18 ++++++++++++++----
> >   1 file changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> > index 76f93614b4cf..1d60f4b8bd09 100644
> > --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> > +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-dev.c
> > @@ -445,17 +445,27 @@ static int rkisp1_entities_register(struct rkisp1_device *rkisp1)
> >
> >   static irqreturn_t rkisp1_isr(int irq, void *ctx)
> >   {
> > +       irqreturn_t ret;
> > +
> >          /*
> >           * Call rkisp1_capture_isr() first to handle the frame that
> >           * potentially completed using the current frame_sequence number before
> >           * it is potentially incremented by rkisp1_isp_isr() in the vertical
> >           * sync.
> >           */
> > -       rkisp1_capture_isr(irq, ctx);
> > -       rkisp1_isp_isr(irq, ctx);
> > -       rkisp1_csi_isr(irq, ctx);
> >
> > -       return IRQ_HANDLED;
> > +       ret = IRQ_NONE;
> > +
> > +       if (rkisp1_capture_isr(irq, ctx) == IRQ_HANDLED)
> > +               ret = IRQ_HANDLED;
> > +
> > +       if (rkisp1_isp_isr(irq, ctx) == IRQ_HANDLED)
> > +               ret = IRQ_HANDLED;
> > +
> > +       if (rkisp1_csi_isr(irq, ctx) == IRQ_HANDLED)
> > +               ret = IRQ_HANDLED;
> > +
>
> It seems like we're throwing away the value of ret each time the
> subsequent if statement is evaluated.  Whether or not they return
> didn't matter before, and the only one that seems using the return
> code is the last one.
>
> Wouldn't it be simpler to use ret = rkisp1_capture_isr(irq, ctx), ret
> = rkisp1_isp_isr(irq, ctx) and ret = rkisp1_csi_isr(irq, ctx) if we
> care about the return code?
>
> How do you expect this to return if one of the first two don't return
> IRQ_HANDLED?

I'm sorry, I don't quite follow what you mean. Can you elaborate a bit?

We want the rkisp1_isr() to return IRQ_NONE if none of the sub-handlers 
handled the interrupt. Otherwise, if any of the sub-handlers return 
IRQ_HANDLED, rkisp1_isr() returns IRQ_HANDLED.

 Tomi