linux-kernel - Re: [PATCH V2 0/2] remoteproc: imx: add start up delay

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Date:   Wed, 2 Nov 2022 11:29:53 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     andersson@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V2 0/2] remoteproc: imx: add start up delay

On Wed, 2 Nov 2022 at 05:23, Peng Fan (OSS) <peng.fan@....nxp.com> wrote:
>
> From: Peng Fan <peng.fan@....com>
>
> V2:
>  Rebased on linux-next
>
> V1:
>  https://lore.kernel.org/lkml/20220609123500.3492475-1-peng.fan@oss.nxp.com/
>
> There is case that after remoteproc start remote processor[M4], the M4
> runs slow and before M4 finish its own rpmsg framework initialization,
> linux sends out vring kick message, then M4 firmware drops the kick
> message. Some NXP released Cortex-M[x] images has such limitation that
> it requires linux sends out vring kick message after M4 firmware finish
> its rpmsg framework initialization.
>
> The best case is to use a method to let M4 notify Linux that M4 has
> finished initialization, but we could not patch released firmware,
> then update driver to detect notification.
>
> So add delay before linux send out vring kick message. It is not good to
> use a fixed time delay in driver, so I choose to get that from device
> tree.
>

>From where I stand this is a hack to hide the lack of motivation to
enact the real solution that is outlined above.  I also wonder how
these problems were not caught during the testing phase.  Either find
a way to upgrade your firmware or keep this in your internal tree.

> Peng Fan (2):
>   dt-bindings: remoteproc: imx_rproc: add fsl,startup-delay-ms
>   remoteproc: imx_rproc: delay after kick remote processor
>
>  .../devicetree/bindings/remoteproc/fsl,imx-rproc.yaml    | 4 ++++
>  drivers/remoteproc/imx_rproc.c                           | 9 +++++++++
>  2 files changed, 13 insertions(+)
>
> --
> 2.37.1
>