linux-kernel - Re: Audio dsp recovery using remoteproc

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Date: Tue, 27 Feb 2024 10:08:27 -0700
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: noman pouigt <variksla@...il.com>
Cc: linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
	alsa-devel@...a-project.org
Subject: Re: Audio dsp recovery using remoteproc

Good day,

On Fri, Feb 16, 2024 at 03:29:56PM -0800, noman pouigt wrote:
> mailbox to dsp_1 is currently modeling platform pcm driver.
> mailbox to dsp_2 is also doing the same.
> 
> Platform driver callbacks cause IPC to be sent to dsp's.
> Lifecycle of two dsp's are managed by separate remoteproc
> drivers. Single sound card is exposed.
> 
> Separate watchdog interrupts from the corresponding dsp's
> are connected to remoteproc to manage crashing of the
> individual dsp's. How can I restart both the dsp when either
> of them crashes using the kernel device model? Remoteproc
> driver currently only restarts the crashed dsp instead of restarting
> both the dsp. It is needed to bring up the hardware in a consistent
> state as both the dsp's are connected to a common hardware.
>

Ok

> I thought of making a virtual parent remoteproc device
> and then managing individual dsp as a subdevice of that parent device
> but remoteproc device node is associated with the individual elf file i.e.
> it can manage only a single dsp.

You are on the right track but perhaps not fully aware of what is already done
for multi core remote processors.  I suggest you have a thorough look at TI's
K3R5 driver[1] and one of it's DTB[2].  In the DTB each remote processor loads a
different firmware file, which seems to be what you are looking for.

Thanks,
Mathieu

[1]. https://elixir.bootlin.com/linux/v6.8-rc6/source/drivers/remoteproc/ti_k3_r5_remoteproc.c
[2]. https://elixir.bootlin.com/linux/v6.8-rc6/source/arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi#L397 


> 
> How can I model remoteproc drivers using linux device model so that when either
> of them crashes both the dsp's get reloaded by the remoteproc framework.
> 
>            MailBox ---- DSP_1 ---
>          |                                    |
> Linux                                      ------ common_hw -> speaker/mic
>           |                                    |
>             MailBox ---- DSP_2 ---
>