Re: [PATCH 1/3] PCI: dwc: Skip allocating own MSI domain if using external MSI domain

[xxm <xxm@xxxxxxxxxxxxxx>]

Hi Robin,

在 2021/1/20 3:47, Robin Murphy 写道:
> On 2021-01-18 09:17, Simon Xue wrote:
> > From: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
> >
> > On some platform, external MSI domain is using instead of the one
> > created by designware driver. For instance, if using GIC-V3-ITS
> > as a MSI domain, we only need set msi-map in the devicetree but
> > never need any bit in the designware driver to handle MSI stuff.
> > So skip allocating its own MSI domain for that case.
>
> How is this different from the existing pp->has_msi_ctrl? AFAICS, 
> dw_pcie_host_init() won't call dw_pcie_allocate_domains() anyway if an 
> external MSI controller is present.

Thanks for your review, I didn't notice pp->has_msi_ctrl already exist, 
will abandon this patch.

Simon Xue.

> Robin.
>
> > Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
> > Signed-off-by: Simon Xue <xxm@xxxxxxxxxxxxxx>
> > ---
> >   drivers/pci/controller/dwc/pcie-designware-host.c | 10 +++++++++-
> >   drivers/pci/controller/dwc/pcie-designware.h      |  1 +
> >   2 files changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c 
> > b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 8a84c005f32b..d9d93cab970a 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -235,6 +235,10 @@ int dw_pcie_allocate_domains(struct pcie_port *pp)
> >       struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> >       struct fwnode_handle *fwnode = 
> > of_node_to_fwnode(pci->dev->of_node);
> >   +    /* Rely on the external MSI domain */
> > +    if (pp->msi_ext)
> > +        return 0;
> > +
> >       pp->irq_domain = irq_domain_create_linear(fwnode, pp->num_vectors,
> >                              &dw_pcie_msi_domain_ops, pp);
> >       if (!pp->irq_domain) {
> > @@ -258,6 +262,9 @@ int dw_pcie_allocate_domains(struct pcie_port *pp)
> >     static void dw_pcie_free_msi(struct pcie_port *pp)
> >   {
> > +    if (pp->msi_ext)
> > +        return;
> > +
> >       if (pp->msi_irq) {
> >           irq_set_chained_handler(pp->msi_irq, NULL);
> >           irq_set_handler_data(pp->msi_irq, NULL);
> > @@ -359,7 +366,8 @@ int dw_pcie_host_init(struct pcie_port *pp)
> >       if (pci->link_gen < 1)
> >           pci->link_gen = of_pci_get_max_link_speed(np);
> >   -    if (pci_msi_enabled()) {
> > +    if (pci_msi_enabled() &&
> > +        !pp->msi_ext) {
> >           pp->has_msi_ctrl = !(pp->ops->msi_host_init ||
> >                        of_property_read_bool(np, "msi-parent") ||
> >                        of_property_read_bool(np, "msi-map"));
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h 
> > b/drivers/pci/controller/dwc/pcie-designware.h
> > index 0207840756c4..cf3b0664302a 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -195,6 +195,7 @@ struct pcie_port {
> >       u32            irq_mask[MAX_MSI_CTRLS];
> >       struct pci_host_bridge  *bridge;
> >       raw_spinlock_t        lock;
> > +    int            msi_ext;
> >       DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
> >   };