Re: [PATCH v3 2/6] PCI: iproc: Add INTx support with better modeling

[Andy Shevchenko]

On Tue, Dec 3, 2019 at 5:55 PM Andrew Murray <andrew.murray@xxxxxxx> wrote:
> On Tue, Dec 03, 2019 at 10:27:02AM +0530, Srinath Mannam wrote:

> > +     /* go through INTx A, B, C, D until all interrupts are handled */
> > +     do {
> > +             status = iproc_pcie_read_reg(pcie, IPROC_PCIE_INTX_CSR);
>
> By performing this read once and outside of the do/while loop you may improve
> performance. I wonder how probable it is to get another INTx whilst handling
> one?

May I ask how it can be improved?
One read will be needed any way, and so does this code.

> > +             for_each_set_bit(bit, &status, PCI_NUM_INTX) {
> > +                     virq = irq_find_mapping(pcie->irq_domain, bit);
> > +                     if (virq)
> > +                             generic_handle_irq(virq);
> > +                     else
> > +                             dev_err(dev, "unexpected INTx%u\n", bit);
> > +             }
> > +     } while ((status & SYS_RC_INTX_MASK) != 0);

-- 
With Best Regards,
Andy Shevchenko