Am Mittwoch, den 31.05.2017, 13:46 +0100 schrieb Joao Pinto:
> Hi Lucas,
>
> Às 1:33 PM de 5/31/2017, Lucas Stach escreveu:
> > Am Dienstag, den 30.05.2017, 12:32 +0100 schrieb Joao Pinto:
> >> This patch adds the new interrupt api to pcie-designware, keeping the old
> >> one. Although the old API is still available, pcie-designware initiates
> >> with the new one.
> >>
> >> Signed-off-by: Joao Pinto <jpinto@xxxxxxxxxxxx>
> >> ---
> > [...]
> >> @@ -378,17 +593,18 @@ int dw_pcie_host_init(struct pcie_port *pp)
> >>
> >> if (IS_ENABLED(CONFIG_PCI_MSI)) {
> >> if (!pp->ops->msi_host_init) {
> >> - pp->irq_domain = irq_domain_add_linear(dev->of_node,
> >> - MAX_MSI_IRQS, &msi_domain_ops,
> >> - &dw_pcie_msi_chip);
> >> - if (!pp->irq_domain) {
> >> - dev_err(dev, "irq domain init failed\n");
> >> - ret = -ENXIO;
> >> + ret = of_property_read_u32(np, "num-vectors",
> >> + &pp->num_vectors);
> >> + if (ret)
> >> + pp->num_vectors = 1;
> >
> > This adds a DT property without documentation. That's a strong no-go.
> >
>
> yep, indeed I forgot to merge this into the patch tree. Going to check this in
> the next patch version.
>
> > Why do you even need this property? The number of vectors available can
> > be inferred from the compatible, so there is no need to push this into
> > the DT. A fallback of only 1 vector if the property doesn't exist is
> > also pretty limiting. The old implementation allowed for at least 32
> > vectors, with most of the core implementations probably allowing much
> > more in hardware.
>
> The hardware supports up to 256, but the current driver is set for a maximum of
> 32. I suggest we remove MAX_MSI_IRQS and MAX_MSI_CTRLS, and calculate the
> maximum number of controllers according to the num_vectors value: Ctrls =
> num_vectors / 32, removing the hardcoded limitation from the driver.
> What do you think?
If you can confirm that all hardware implementations of the DWC PCIe
core support 256 vectors, I don't see a reason to ever expose less than
this. I guess the current limit of 32 hasn't been raised out of fear
that some hardware implementations might not support the full range of
256 vectors.
You are in a much better position to validate this than I am. I fully
support removing artificial limits from the driver implementation.
Regards,
Lucas
