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Date:   Tue, 28 Jul 2020 09:20:06 +0200
From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Peng Fan <peng.fan@nxp.com>
Cc:     "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "mathieu.poirier@linaro.org" <mathieu.poirier@linaro.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
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        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH 03/10] remoteproc: imx: use devm_ioremap
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On Mon, Jul 27, 2020 at 08:11:09AM +0000, Peng Fan wrote:
> > Subject: Re: [PATCH 03/10] remoteproc: imx: use devm_ioremap
> >=20
> > On Mon, Jul 27, 2020 at 06:51:00AM +0000, Peng Fan wrote:
> > > > Subject: Re: [PATCH 03/10] remoteproc: imx: use devm_ioremap
> > > >
> > > > On Mon, Jul 27, 2020 at 06:28:20AM +0000, Peng Fan wrote:
> > > > > Hi Oleksij,
> > > > >
> > > > > > Subject: Re: [PATCH 03/10] remoteproc: imx: use devm_ioremap
> > > > > >
> > > > > > On Fri, Jul 24, 2020 at 04:08:06PM +0800, Peng Fan wrote:
> > > > > > > We might need to map an region multiple times, becaue the
> > > > > > > region might be shared between remote processors, such i.MX8QM
> > > > > > > with dual
> > > > M4 cores.
> > > > > > > So use devm_ioremap, not devm_ioremap_resource.
> > > > > >
> > > > > > Can you please give an example of this kind of shared resources
> > > > > > and how they should be handled by two separate devices?
> > > > >
> > > > > This is to share vdevbuffer space, there is a vdevbuffer in device
> > > > > tree, it will be shared between M4_0 and M4_1.
> > > > >
> > > > > For the buffer, it is Linux DMA API will handle the space.
> > > >
> > > > Why remoteproc need to care about it? If I see it correctly, from
> > > > the linux perspective, it is one buffer and one driver is
> > > > responsible for it. Or do I missing some thing?
> > >
> > > We not have the vdev buffer in resource table, so I added in device t=
ree, see
> > below:
> >=20
> > Hm.. if vdev is not in resource table and should not be controlled by
> > remoteproc, why do we need remoteproc?
>=20
> I use same approach as stm32 rproc driver.
>=20
> The resource table here only publish vring address.
>=20
> >=20
> > >         imx8qm_cm40: imx8qm_cm4@0 {
> > >                 compatible =3D "fsl,imx8qm-cm4";
> > >                 rsc-da =3D <0x90000000>;
> > >                 mbox-names =3D "tx", "rx", "rxdb";
> > >                 mboxes =3D <&lsio_mu5 0 1
> > >                           &lsio_mu5 1 1
> > >                           &lsio_mu5 3 1>;
> > >                 mub-partition =3D <3>;
> > >                 memory-region =3D <&vdev0vring0>, <&vdev0vring1>,
> > <&vdevbuffer>,
> > >                                 <&vdev1vring0>, <&vdev1vring1>;
> > >                 core-index =3D <0>;
> > >                 core-id =3D <IMX_SC_R_M4_0_PID0>;
> > >                 status =3D "okay";
> > >                 power-domains =3D <&pd IMX_SC_R_M4_0_PID0>,
> > >                                 <&pd IMX_SC_R_M4_0_MU_1A>;
> > >         };
> > >
> > >         imx8qm_cm41: imx8x_cm4@1 {
> > >                 compatible =3D "fsl,imx8qm-cm4";
> > >                 rsc-da =3D <0x90100000>;
> > >                 mbox-names =3D "tx", "rx", "rxdb";
> > >                 mboxes =3D <&lsio_mu6 0 1
> > >                           &lsio_mu6 1 1
> > >                           &lsio_mu6 3 1>;
> > >                 mub-partition =3D <4>;
> > >                 memory-region =3D <&vdev2vring0>, <&vdev2vring1>,
> > <&vdevbuffer>,
> > >                                 <&vdev3vring0>, <&vdev3vring1>;
> > >                 core-index =3D <1>;
> > >                 core-id =3D <IMX_SC_R_M4_1_PID0>;
> > >                 status =3D "okay";
> > >                 power-domains =3D <&pd IMX_SC_R_M4_1_PID0>,
> > >                                 <&pd IMX_SC_R_M4_1_MU_1A>;
> > >         };
> > >
> > >                 vdevbuffer: vdevbuffer {
> > >                         compatible =3D "shared-dma-pool";
> > >                         reg =3D <0 0x90400000 0 0x100000>;
> > >                         no-map;
> > >                 };
> > >
> > > I have the upper vdevbuffer node shared between M40 and M41 node.
> > > The vdevbuffer will be used as virtio data buffer.
> > >
> > > And I have the following in rproc_add_virtio_dev to share vdevbuffer:
> > >         /* Try to find dedicated vdev buffer carveout */
> > >         mem =3D rproc_find_carveout_by_name(rproc, "vdev%dbuffer",
> > rvdev->index);
> > >         if (!mem)
> > >                 mem =3D rproc_find_carveout_by_name(rproc,
> > > "vdevbuffer");
> >=20
> > With kernel v5.8-rc7 i get following call chain:
>=20
> Please use Linux-next which has support of M4 booted before Linux in
> in remoteproc.
>=20
> > rproc_boot()
> >   rproc_fw_boot()
> >     rproc_handle_vdev
> >       rproc_vdev_do_start()
> >         rproc_add_virtio_dev()
> >=20
> >=20
> > So, at the end, we will call rproc_add_virtio_dev() only if we boot fir=
mware by
> > linux, or if we get at least the resource table.
>=20
>=20
> Resource table could be got from elf file if it is booted by Linux, or go=
t from
> an address if M4 is booted before Linux.

Ok, i see now. Thank you!

Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>

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