Date:   Fri, 17 Apr 2020 11:57:20 +0300
From:   Nikita Shubin <nikita.shubin@...uefel.me>
To:     Peng Fan <peng.fan@....com>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] remoteproc: imx_rproc: add virtio support

On Wed, 15 Apr 2020 02:42:32 +0000
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 don't see anything that allows booting imx7-m4 from A7 In case elf
file interrupt vector is not supposed to be at OCRAM_S, am i missing
something?

I not interested in booting A7 from M4, i interested in wise versa
scenario.

> I have been waiting for Mathieu's rproc sync state patch, then
> rebase.
> 
> 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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