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Date:   Wed, 2 Aug 2023 21:25:15 +0100
From:   Conor Dooley <conor@kernel.org>
To:     Tomasz Jeznach <tjeznach@rivosinc.com>
Cc:     Zong Li <zong.li@sifive.com>, Joerg Roedel <joro@8bytes.org>,
        Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Anup Patel <apatel@ventanamicro.com>,
        Albert Ou <aou@eecs.berkeley.edu>, linux@rivosinc.com,
        linux-kernel@vger.kernel.org, Sebastien Boeuf <seb@rivosinc.com>,
        iommu@lists.linux.dev, Palmer Dabbelt <palmer@dabbelt.com>,
        Nick Kossifidis <mick@ics.forth.gr>,
        linux-riscv@lists.infradead.org
Subject: Re: [PATCH 01/11] RISC-V: drivers/iommu: Add RISC-V IOMMU - Ziommu
 support.
Message-ID: <20230802-maimed-spotted-5fa1fe4be386@spud>
References: <cover.1689792825.git.tjeznach@rivosinc.com>
 <c33c24036c06c023947ecb47177da273569b3ac7.1689792825.git.tjeznach@rivosinc.com>
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On Wed, Aug 02, 2023 at 01:15:22PM -0700, Tomasz Jeznach wrote:
> On Thu, Jul 27, 2023 at 7:42=E2=80=AFPM Zong Li <zong.li@sifive.com> wrot=
e:
> >
> > On Thu, Jul 20, 2023 at 3:34=E2=80=AFAM Tomasz Jeznach <tjeznach@rivosi=
nc.com> wrote:
> > >
> > > +static int riscv_iommu_platform_probe(struct platform_device *pdev)
> > > +{
> > > +       struct device *dev =3D &pdev->dev;
> > > +       struct riscv_iommu_device *iommu =3D NULL;
> > > +       struct resource *res =3D NULL;
> > > +       int ret =3D 0;
> > > +
> > > +       iommu =3D devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
> > > +       if (!iommu)
> > > +               return -ENOMEM;
> > > +
> > > +       iommu->dev =3D dev;
> > > +       dev_set_drvdata(dev, iommu);
> > > +
> > > +       res =3D platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > +       if (!res) {
> > > +               dev_err(dev, "could not find resource for register re=
gion\n");
> > > +               return -EINVAL;
> > > +       }
> > > +
> > > +       iommu->reg =3D devm_platform_get_and_ioremap_resource(pdev, 0=
, &res);
> > > +       if (IS_ERR(iommu->reg)) {
> > > +               ret =3D dev_err_probe(dev, PTR_ERR(iommu->reg),
> > > +                                   "could not map register region\n"=
);
> > > +               goto fail;
> > > +       };
> > > +
> > > +       iommu->reg_phys =3D res->start;
> > > +
> > > +       ret =3D -ENODEV;
> > > +
> > > +       /* Sanity check: Did we get the whole register space ? */
> > > +       if ((res->end - res->start + 1) < RISCV_IOMMU_REG_SIZE) {
> > > +               dev_err(dev, "device region smaller than register fil=
e (0x%llx)\n",
> > > +                       res->end - res->start);
> > > +               goto fail;
> > > +       }
> >
> > Could we assume that DT should be responsible for specifying the right =
size?
> >
>=20
> This only to validate DT provided info and driver expected register
> file size. Expectation is that DT will provide right size.

FWIW this check seems needless to me, it's not the kernels job to
validate the devicetree.


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