On Tue, 26 Jul 2022 22:48:32 +0100,
Frank Li <frank.li@xxxxxxx> wrote:
>
> > > > > +static void imx_mu_msi_irq_handler(struct irq_desc *desc)
> > > > > +{
> > > > > + struct imx_mu_msi *msi_data = irq_desc_get_handler_data(desc);
> > > > > + u32 status;
> > > > > + int i;
> > > > > +
> > > > > + status = imx_mu_read(msi_data, msi_data->cfg-
> > >xSR[IMX_MU_RSR]);
> > > > > +
> > > > > + chained_irq_enter(irq_desc_get_chip(desc), desc);
> > > > > + for (i = 0; i < IMX_MU_CHANS; i++) {
> > > > > + if (status & IMX_MU_xSR_RFn(msi_data->cfg->type, i)) {
> > > > > + imx_mu_read(msi_data, msi_data->cfg->xRR + i * 4);
> > > > > + generic_handle_domain_irq(msi_data->parent, i);
> > > >
> > > > Why the parent? You must start at the top of the hierarchy.
>
> [Frank Li] Do you means that should be msi_data->msi_domain instead
> of msi_data->parent?
Indeed. you must *not* bypass the hierarchy, and the top level of the
hierarchy has to implement whatever is required by the interrupt flow.
>
> > > >
> > > > > + }
> > > > > + }
> > > > > + chained_irq_exit(irq_desc_get_chip(desc), desc);
> > > >
> > > > If your MSIs are a chained interrupt, why do you even provide an
> > > > affinity setting callback?
> > >
> > > [Frank Li] it will be crash if no affinity setting callback.
> >
> > Then you have to fix your driver.
>
> [Frank Li] After debug, msi_domain_set_affinity() have not did null check for (parent->chip->irq_set_affinity).
> I think impact by using dummy set_affinity is minimized.
>
> int msi_domain_set_affinity(struct irq_data *irq_data,
> const struct cpumask *mask, bool force)
> {
> struct irq_data *parent = irq_data->parent_data;
> struct msi_msg msg[2] = { [1] = { }, };
> int ret;
>
> ret = parent->chip->irq_set_affinity(parent, mask, force);
> if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE) {
> BUG_ON(irq_chip_compose_msi_msg(irq_data, msg));
> msi_check_level(irq_data->domain, msg);
> irq_chip_write_msi_msg(irq_data, msg);
> }
>
> return ret;
> }
No. Changing the affinity of an interrupt must not affect the affinity
of another. Given that this is a chained handler, you *cannot* satisfy
this requirement. So you can't change the affinity at all.
N,
--
Without deviation from the norm, progress is not possible.
