On Tue, 2018-11-13 at 22:57 +0000, Marc Zyngier wrote:
> The write to the status register is really an ACK for the HW,
> and should be treated as such by the driver. Let's move it to the
> irq_ack callback, which will prevent people from moving it around
> in order to paper over other bugs.
>
>
> static void dw_pci_bottom_ack(struct irq_data *d)
> {
> - struct msi_desc *msi = irq_data_get_msi_desc(d);
> - struct pcie_port *pp;
> + struct pcie_port *pp = irq_data_get_irq_chip_data(d);
> + unsigned int res, bit, ctrl;
> unsigned long flags;
>
> - pp = msi_desc_to_pci_sysdata(msi);
> + ctrl = d->hwirq / MAX_MSI_IRQS_PER_CTRL;
> + res = ctrl * MSI_REG_CTRL_BLOCK_SIZE;
> + bit = d->hwirq % MAX_MSI_IRQS_PER_CTRL;
>
> raw_spin_lock_irqsave(&pp->lock, flags);
>
> + dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_STATUS + res, 4, 1 << bit);
Does this need to be inside the lock? The single write should allow
for an atomic clear without need for a lock.
> +
> if (pp->ops->msi_irq_ack)
> pp->ops->msi_irq_ack(d->hwirq, pp);
And couldn't the lock be inside the if here, so that it is never taken
if there is no platform specific handler?
