Re: [PATCH 06/11] RISC-V: drivers/iommu/riscv: Add command, fault, page-req queues

[Nick Kossifidis]

On 7/29/23 15:58, Zong Li wrote:
> On Thu, Jul 20, 2023 at 3:34 AM Tomasz Jeznach <tjeznach@xxxxxxxxxxxx> wrote:
> > +       iommu->cap = riscv_iommu_readq(iommu, RISCV_IOMMU_REG_CAP);
> > +
> > +       /* For now we only support WSIs until we have AIA support */
>
> I'm not completely understand AIA support here, because I saw the pci
> case uses the MSI, and kernel seems to have the AIA implementation.
> Could you please elaborate it?

When I wrote this we didn't have AIA in the kernel, and without IMSIC we 
can't have MSIs in the hart (we can still have MSIs in the PCIe controller).

> Should we define the "interrupt-names" in dt-bindings?

Yes we should, along with queue lengths below.

> > +
> > +       /* Make sure fctl.WSI is set */
> > +       fctl = riscv_iommu_readl(iommu, RISCV_IOMMU_REG_FCTL);
> > +       fctl |= RISCV_IOMMU_FCTL_WSI;
> > +       riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FCTL, fctl);
> > +
> > +       /* Parse Queue lengts */
> > +       ret = of_property_read_u32(pdev->dev.of_node, "cmdq_len", &iommu->cmdq_len);
> > +       if (!ret)
> > +               dev_info(dev, "command queue length set to %i\n", iommu->cmdq_len);
> > +
> > +       ret = of_property_read_u32(pdev->dev.of_node, "fltq_len", &iommu->fltq_len);
> > +       if (!ret)
> > +               dev_info(dev, "fault/event queue length set to %i\n", iommu->fltq_len);
> > +
> > +       ret = of_property_read_u32(pdev->dev.of_node, "priq_len", &iommu->priq_len);
> > +       if (!ret)
> > +               dev_info(dev, "page request queue length set to %i\n", iommu->priq_len);
> > +
> >          dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));