RE: [PATCH 00/10] remoteproc: imx_rproc: support iMX8M and early boot

[Peng Fan <peng.fan@nxp.com>]

> Subject: Re: [PATCH 00/10] remoteproc: imx_rproc: support iMX8M and early
> boot
> 
> On Mon, Jul 27, 2020 at 06:44:32AM +0000, Peng Fan wrote:
> > Hi Oleksij,
> >
> > > Subject: Re: [PATCH 00/10] remoteproc: imx_rproc: support iMX8M and
> > > early boot
> > >
> > > Hi,
> > >
> > > On Fri, Jul 24, 2020 at 04:08:03PM +0800, Peng Fan wrote:
> > > > This patchset is to support i.MX8MQ/M coproc booted before linux.
> > > > Since i.MX8MQ/M was not supported, several patches are needed to
> > > > first support the platform, then support early boot case.
> > > >
> > > > I intended to included i.MX8QM/QXP, but that would introduce a
> > > > large patchset, so not included. But the clk/syscon optional patch
> > > > for i.MX8QM/QXP was still kept here to avoid rebase error.
> > >
> > > Thank you for your work.
> > >
> > > Can you please provide more information about big picture of this work.
> > >
> > > If I see it correctly, we have here support for i.MX8MM, which seems
> > > to be able to fully control Cortex M4 (enable CPU core, etc...).
> >
> > Yes.
> 
> In this case, I would recommend to mainline the i.MX8MM part
> first/separately.

Only the last patch is to support earlyboot, all others is imx8mm part.

> 
> > >
> > > And other case, where remoteproc is running on application processor
> > > and can't or should not touch M4 (i.MX7ULP, i.MX8QM/QXP..). Since M4
> > > provides some functionality, you are trying to reuse remoteproc
> > > framework to get resource table present in ELF header and to
> > > dynamically load things. For some reasons this header provides more
> > > information then needed, so you are changing the ELF parser in the kernel
> to workaround it.
> >
> > Not exactly.
> >
> > For i.MX8MM, we support two cases. M4 kicked by U-Boot, M4 kicked by
> Linux remoteproc.
> > For i.MX8QM/QXP, the typical usecase is M4 kicked by SCFW, but we will
> > also add M4 kicked by Linux remoteproc.
> > For i.MX7ULP, I would only support M4 dual boot case, M4 control
> everything.
> 
> From current state of discussion, i'm not sure what role plays remoteproc in
> the scenario where M4 is started before linux. Especially if we are not using
> resource table.

We are using resource table from an address, not in elf file.
This is the new feature in Linux-next to support coproc booted early.

> 
> > The reason the change the elf parser is that when M4 elf is loaded by
> > Linux remoteproc, It use memset to clear area.
> 
> The use of memset, depends on ELF format. Fix/change the linker script on
> your firmware and memset will be never called.
> 
> > However we use ioremap, memset on ARM64 will report crash to device
> > nGnRE memory. And we could not use ioremap_wc to TCM area, since it
> > could have data correctly written into TCM.
> 
> I have strong feeling, that we are talking about badly or not properly
> formatted ELF binary. I would prefer to double check it, before we will apply
> fixes on wrong place.
> 
> > Maintainer not wanna to drop memset in common code, and TI guys
> > suggest add i.MX specific elf stuff. So I add elf handler in i.MX code.
> 
> I think, removing memset may damage current users of imx_rproc driver.
> Since, like I said: the use of memset depends on ELF format.

In my elf file, the last PT_LOAD contains data/bss/heap/stack. I'll check
with our MCU guys, we only need the specific data loaded.

Elf file type is EXEC (Executable file)
Entry point 0x1ffe0355
There are 3 program headers, starting at offset 52

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  LOAD           0x010000 0x1ffe0000 0x1ffe0000 0x00240 0x00240 R   0x10000
  LOAD           0x010240 0x1ffe0240 0x1ffe0240 0x03e90 0x03e90 RWE 0x10000
  LOAD           0x020000 0x20000000 0x1ffe40d0 0x00068 0x0ad00 RW  0x10000

 Section to Segment mapping:
  Segment Sections...
   00     .interrupts
   01     .resource_table .text .ARM .init_array .fini_array
   02     .data .bss .heap .stack

Thanks,
Peng.

> 
> > Thanks,
> > Peng.
> >
> > >
> > > Correct?
> > >
> > > > Peng Fan (10):
> > > >   dt-bindings: remoteproc: imx_rproc: add i.MX8MQ/M
> > > >   remoteproc: imx_rproc: correct err message
> > > >   remoteproc: imx: use devm_ioremap
> > > >   remoteproc: imx_rproc: make syscon optional
> > > >   remoteproc: imx_rproc: make clk optional
> > > >   remoteproc: imx_rproc: add load hook
> > > >   remoteproc: imx_rproc: add i.MX specific parse fw hook
> > > >   remoteproc: imx_rproc: support i.MX8MQ/M
> > > >   remoteproc: imx_proc: enable virtio/mailbox
> > > >   remoteproc: imx_rproc: support coproc booting before Linux
> > > >
> > > >  .../devicetree/bindings/remoteproc/imx-rproc.txt   |   3 +
> > > >  drivers/remoteproc/imx_rproc.c                     | 409
> > > ++++++++++++++++++++-
> > > >  2 files changed, 401 insertions(+), 11 deletions(-)
> > > >
> > > > --
> > > > 2.16.4
> > > >
> > > >
> > > > _______________________________________________
> > > > linux-arm-kernel mailing list
> > > > linux-arm-kernel@lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> > > >
> > >
> > > --
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> 
> --
> Pengutronix e.K.                           |
> |
> Steuerwalder Str. 21                       |
> http://www.pengutronix.de/  |
> 31137 Hildesheim, Germany                  | Phone:
> +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:
> +49-5121-206917-5555 |