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

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Message-ID: <CANXhq0puxuHA2cEyb2+TobkoFTc=7MQqtv7DYbuZdvf0T8+iUQ@mail.gmail.com>
Date:   Mon, 31 Jul 2023 21:15:53 +0800
From:   Zong Li <zong.li@...ive.com>
To:     Nick Kossifidis <mick@....forth.gr>
Cc:     Tomasz Jeznach <tjeznach@...osinc.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Anup Patel <apatel@...tanamicro.com>,
        Albert Ou <aou@...s.berkeley.edu>, linux@...osinc.com,
        linux-kernel@...r.kernel.org, Sebastien Boeuf <seb@...osinc.com>,
        iommu@...ts.linux.dev, Palmer Dabbelt <palmer@...belt.com>,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 06/11] RISC-V: drivers/iommu/riscv: Add command, fault,
 page-req queues

On Mon, Jul 31, 2023 at 5:32 PM Nick Kossifidis <mick@....forth.gr> wrote:
>
> On 7/29/23 15:58, Zong Li wrote:
> > On Thu, Jul 20, 2023 at 3:34 AM Tomasz Jeznach <tjeznach@...osinc.com> 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).

Thanks for your clarification, do we support the MSI in next version?

>
> >
> > 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));
> >>