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Date:   Mon, 27 Jul 2020 09:54:41 +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>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "festevam@gmail.com" <festevam@gmail.com>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 00/10] remoteproc: imx_rproc: support iMX8M and early boot
Message-ID: <20200727075441.lgscydoj3txupeay@pengutronix.de>
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On Mon, Jul 27, 2020 at 06:44:32AM +0000, Peng Fan wrote:
> Hi Oleksij,
>=20
> > Subject: Re: [PATCH 00/10] remoteproc: imx_rproc: support iMX8M and ear=
ly
> > boot
> >=20
> > Hi,
> >=20
> > 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.
> >=20
> > Thank you for your work.
> >=20
> > Can you please provide more information about big picture of this work.
> >=20
> > 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...).
>=20
> Yes.

In this case, I would recommend to mainline the i.MX8MM part
first/separately.

> >=20
> > 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 provid=
es
> > some functionality, you are trying to reuse remoteproc framework to get
> > resource table present in ELF header and to dynamically load things. Fo=
r some
> > reasons this header provides more information then needed, so you are
> > changing the ELF parser in the kernel to workaround it.
>=20
> Not exactly.
>=20
> For i.MX8MM, we support two cases. M4 kicked by U-Boot, M4 kicked by Linu=
x remoteproc.
> For i.MX8QM/QXP, the typical usecase is M4 kicked by SCFW, but we will al=
so add M4 kicked
> by Linux remoteproc.
> For i.MX7ULP, I would only support M4 dual boot case, M4 control everythi=
ng.

=46rom 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.

> The reason the change the elf parser is that when M4 elf is loaded by Lin=
ux 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.

> Thanks,
> Peng.
>=20
> >=20
> > Correct?
> >=20
> > > 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
> > >
> >=20
> > --
> > 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 |

--=20
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 |

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