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 tree, see below:
Hm.. if vdev is not in resource table and should not be controlled by
remoteproc, why do we need remoteproc?
> imx8qm_cm40: imx8qm_cm4@0 {
> compatible = "fsl,imx8qm-cm4";
> rsc-da = <0x90000000>;
> mbox-names = "tx", "rx", "rxdb";
> mboxes = <&lsio_mu5 0 1
> &lsio_mu5 1 1
> &lsio_mu5 3 1>;
> mub-partition = <3>;
> memory-region = <&vdev0vring0>, <&vdev0vring1>, <&vdevbuffer>,
> <&vdev1vring0>, <&vdev1vring1>;
> core-index = <0>;
> core-id = <IMX_SC_R_M4_0_PID0>;
> status = "okay";
> power-domains = <&pd IMX_SC_R_M4_0_PID0>,
> <&pd IMX_SC_R_M4_0_MU_1A>;
> };
>
> imx8qm_cm41: imx8x_cm4@1 {
> compatible = "fsl,imx8qm-cm4";
> rsc-da = <0x90100000>;
> mbox-names = "tx", "rx", "rxdb";
> mboxes = <&lsio_mu6 0 1
> &lsio_mu6 1 1
> &lsio_mu6 3 1>;
> mub-partition = <4>;
> memory-region = <&vdev2vring0>, <&vdev2vring1>, <&vdevbuffer>,
> <&vdev3vring0>, <&vdev3vring1>;
> core-index = <1>;
> core-id = <IMX_SC_R_M4_1_PID0>;
> status = "okay";
> power-domains = <&pd IMX_SC_R_M4_1_PID0>,
> <&pd IMX_SC_R_M4_1_MU_1A>;
> };
>
> vdevbuffer: vdevbuffer {
> compatible = "shared-dma-pool";
> reg = <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 = rproc_find_carveout_by_name(rproc, "vdev%dbuffer", rvdev->index);
> if (!mem)
> mem = rproc_find_carveout_by_name(rproc, "vdevbuffer");
With kernel v5.8-rc7 i get following call chain:
rproc_boot()
rproc_fw_boot()
rproc_handle_vdev
rproc_vdev_do_start()
rproc_add_virtio_dev()
So, at the end, we will call rproc_add_virtio_dev() only if we boot
firmware by linux, or if we get at least the resource table.
Since none of this seems to be the case, i still do not understand how
it should work.
> Hope this is clear.
:) i still need some time to understand it.
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