Date:   Wed, 15 Apr 2020 10:26:04 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Peng Fan <peng.fan@....com>
Cc:     "nikita.shubin@...uefel.me" <nikita.shubin@...uefel.me>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        dl-linux-imx <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 0/3] remoteproc: imx_rproc: add virtio support

On Tue, 14 Apr 2020 at 20:42, Peng Fan <peng.fan@....com> wrote:
>
> > Subject: [PATCH v2 0/3] remoteproc: imx_rproc: add virtio support
>
> Have you ever see https://patchwork.kernel.org/cover/11390477/?
>
> I have been waiting for Mathieu's rproc sync state patch, then
> rebase.

I have already sent out 2 revisions of the MCU synchronisation
patchset, the latest here [1].  A new iteration should be out by the
end of the week or early next week.  When that happens, I would really
appreciate it if you could take a look and provide comments.

Thanks,
Mathieu

[1].https://patchwork.kernel.org/project/linux-remoteproc/list/?series=261069


>
> Thanks,
> Peng.
>
> >
> > This patch set introduces virtio support for imx7d-m4 communication:
> >
> > - support booting loaded vim imx-rproc firmware
> > - implement .kick method support using mailbox in imx-processor
> > - parse vdev0vring0, vdev0vring1, vdev0buffer memory regions required for
> > virtio_rpmsg_bus initialization
> >
> > Regarding imx7d-m4 boot proccess
> >
> > Citing ARM documentation:
> >
> > At Reset, Cortex-M3 and Cortex-M4 processors always boot from a vector
> > table at address zero.
> >
> > "With uninitialized memory at address zero (for example, unprogrammed
> > Flash or uninitialized RAM), the processor will read a spurious initial Main
> > Stack Pointer value from address zero and a spurious code entry point (Reset
> > vector) from address 0x4, possibly containing an illegal instruction set state
> > specifier (ESPR.T bit) in bit[0]."
> >
> > So to successfully boot m4 coproc we need to write Stack Pointer and
> > Program counter, i see no obvious to get Stack Pointer value, so two ways
> > exist ethier form a special elf section:
> >
> > "
> > .loader :
> >   {
> >     LONG(__StackTop);
> >     LONG(Reset_Handler + 1);
> >   } > m_start
> > "
> >
> > and put it at 0x0 address:
> >
> > "
> > m_start               (RX)  : ORIGIN = 0x00000000, LENGTH =
> > 0x00008000
> > "
> >
> > Or (the way i've chosen) only put Entry Point at 0x04 and set stack as first
> > instruction:
> >
> > "
> > Reset_Handler:
> >       ldr   sp, =__stack      /* set stack pointer */
> > "
> >
> > Regarding mailboxes and memory regions :
> >
> > This code is heavily derived from stm32-rproc (i.e. copy pasted) and this fact
> > needs to reflected in commits, please tell me how to emphasize this fact.
> >
> > Attaching succesful trace booting m4 (with Add rpmsg tty driver applied) :
> >
> > [  143.240616] remoteproc remoteproc0: powering up imx-rproc
> > [  143.251768] remoteproc remoteproc0: Booting fw image huginn.elf, size
> > 466876 [  143.251786] imx-rproc imx7d-cm4: iommu not present
> > [  143.251825] remoteproc remoteproc0: rsc: type 3 [  143.251837]
> > remoteproc remoteproc0: vdev rsc: id 7, dfeatures 0x1, cfg len 0, 2 vrings
> > [  143.251924] remoteproc remoteproc0: vdev rsc: vring0: da 0xffffffff, qsz
> > 16, align 16 [  143.251935] remoteproc remoteproc0: vdev rsc: vring1: da
> > 0xffffffff, qsz 16, align 16 [  143.251955] imx-rproc imx7d-cm4: map memory:
> > 0x00900000+20000 [  143.251987] imx-rproc imx7d-cm4: map memory:
> > 0x00920000+2000 [  143.252003] imx-rproc imx7d-cm4: map memory:
> > 0x00922000+2000 [  143.252020] remoteproc remoteproc0: phdr: type 1 da
> > 0x20200000 memsz 0x240 filesz 0x240 [  143.252032] remoteproc
> > remoteproc0: da = 0x20200000 len = 0x240 va = 0x(ptrval) [  143.252043]
> > remoteproc remoteproc0: phdr: type 1 da 0x20200240 memsz 0x5b38 filesz
> > 0x5b38 [  143.252053] remoteproc remoteproc0: da = 0x20200240 len =
> > 0x5b38 va = 0x(ptrval) [  143.252105] remoteproc remoteproc0: phdr: type
> > 1 da 0x20205d78 memsz 0x4b58 filesz 0x758 [  143.252115] remoteproc
> > remoteproc0: da = 0x20205d78 len = 0x4b58 va = 0x(ptrval) [  143.252159]
> > remoteproc remoteproc0: da = 0x200006cc len = 0x8c va = 0x(ptrval)
> > [  143.252176] remoteproc remoteproc0: Started from 0x202002f5
> > [  143.252211]  imx7d-cm4#vdev0buffer: assigned reserved memory node
> > vdev0buffer@...24000 [  143.252232] virtio virtio0: reset !
> > [  143.252241] virtio virtio0: status: 1 [  143.260567] virtio_rpmsg_bus
> > virtio0: status: 3 [  143.260598] remoteproc remoteproc0: vring0: va
> > c083c000 qsz 16 notifyid 0 [  143.260614] remoteproc remoteproc0: vring1:
> > va c0872000 qsz 16 notifyid 1 [  143.260651] virtio_rpmsg_bus virtio0:
> > buffers: va c0894000, dma 0x00924000 [  143.260666] Added buffer head 0
> > to (ptrval) [  143.260674] Added buffer head 1 to (ptrval) [  143.260680]
> > Added buffer head 2 to (ptrval) [  143.260686] Added buffer head 3 to (ptrval)
> > [  143.260692] Added buffer head 4 to (ptrval) [  143.260697] Added buffer
> > head 5 to (ptrval) [  143.260703] Added buffer head 6 to (ptrval)
> > [  143.260709] Added buffer head 7 to (ptrval) [  143.260715] Added buffer
> > head 8 to (ptrval) [  143.260721] Added buffer head 9 to (ptrval)
> > [  143.260727] Added buffer head 10 to (ptrval) [  143.260733] Added
> > buffer head 11 to (ptrval) [  143.260738] Added buffer head 12 to (ptrval)
> > [  143.260744] Added buffer head 13 to (ptrval) [  143.260750] Added
> > buffer head 14 to (ptrval) [  143.260756] Added buffer head 15 to (ptrval)
> > [  143.260771] virtio_rpmsg_bus virtio0: status: 7 [  143.260779]
> > remoteproc remoteproc0: kicking vq index: 0 [  143.260788] remoteproc
> > remoteproc0: sending message : vqid = 0 [  143.260802] imx_mu
> > 30aa0000.mailbox: Send data on wrong channel type: 1 [  143.260810]
> > virtio_rpmsg_bus virtio0: rpmsg host is online [  143.261680]
> > imx7d-cm4#vdev0buffer: registered virtio0 (type 7) [  143.261694]
> > remoteproc remoteproc0: remote processor imx-rproc is now up
> > [  143.354880] remoteproc remoteproc0: vq index 0 is interrupted
> > [  143.354895] virtqueue callback for (ptrval) ((ptrval)) [  143.354912]
> > virtio_rpmsg_bus virtio0: From: 0x0, To: 0x35, Len: 40, Flags: 0, Reserved: 0
> > [  143.354924] rpmsg_virtio RX: 00 00 00 00 35 00 00 00 00 00 00 00 28 00
> > 00 00  ....5.......(...
> > [  143.354932] rpmsg_virtio RX: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77 00
> > 00 00  rpmsg-tty-raw...
> > [  143.354939] rpmsg_virtio RX: 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > 00 00  ................
> > [  143.354945] rpmsg_virtio RX: 00 00 00 00 00 00 00
> > 00                          ........
> > [  143.354956] NS announcement: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77
> > 00 00 00  rpmsg-tty-raw...
> > [  143.354963] NS announcement: 00 00 00 00 00 00 00 00 00 00 00 00 00
> > 00 00 00  ................
> > [  143.354969] NS announcement: 00 00 00 00 00 00 00
> > 00                          ........
> > [  143.354980] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty-raw
> > addr 0x0 [  143.356584] rpmsg_tty virtio0.rpmsg-tty-raw.-1.0: new channel:
> > 0x400 -> 0x0 : ttyRPMSG0 [  143.356651] Added buffer head 0 to (ptrval)
> > [  143.356658] No more buffers in queue [  143.356667] virtio_rpmsg_bus
> > virtio0: Received 1 messages [  143.404302] remoteproc remoteproc0: vq
> > index 0 is interrupted [  143.404319] virtqueue callback for (ptrval) ((ptrval))
> > [  143.404337] virtio_rpmsg_bus virtio0: From: 0x1, To: 0x35, Len: 40, Flags:
> > 0, Reserved: 0 [  143.404350] rpmsg_virtio RX: 01 00 00 00 35 00 00 00 00
> > 00 00 00 28 00 00 00  ....5.......(...
> > [  143.404391] rpmsg_virtio RX: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77 00
> > 00 00  rpmsg-tty-raw...
> > [  143.404399] rpmsg_virtio RX: 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > 00 00  ................
> > [  143.404405] rpmsg_virtio RX: 01 00 00 00 00 00 00
> > 00                          ........
> > [  143.404417] NS announcement: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77
> > 00 00 00  rpmsg-tty-raw...
> > [  143.404424] NS announcement: 00 00 00 00 00 00 00 00 00 00 00 00 00
> > 00 00 00  ................
> > [  143.404430] NS announcement: 01 00 00 00 00 00 00
> > 00                          ........
> > [  143.404441] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty-raw
> > addr 0x1 [  143.411114] rpmsg_tty virtio0.rpmsg-tty-raw.-1.1: new channel:
> > 0x401 -> 0x1 : ttyRPMSG1
>
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