linux-kernel - Re: [PATCH v2] remoteproc: Introduce prepare/unprepare ops for rproc coredump

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Message-ID: <20180529050523.GG2259@tuxbook-pro>
Date:   Mon, 28 May 2018 22:05:23 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     ohad@...ery.com, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2] remoteproc: Introduce prepare/unprepare ops for rproc
 coredump

On Mon 21 May 11:45 PDT 2018, Sibi Sankar wrote:

> In some occasions the remoteproc device might need to
> prepare some hardware before the coredump can be performed
> and cleanup the state afterwards.
> 
> Q6V5 modem requires the mba to be loaded before the
> coredump and some cleanup of the resources afterwards.
> 

This describes two different changes, so please put it in two+ patches.

[..]
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index dfdaede9139e..010819e01279 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -333,6 +333,8 @@ struct firmware;
>   * @kick:	kick a virtqueue (virtqueue id given as a parameter)
>   * @da_to_va:	optional platform hook to perform address translations
>   * @load_rsc_table:	load resource table from firmware image
> + * @prepare_coredump:	prepare function, called before coredump
> + * @unprepare_coredump:	unprepare function, called post coredump

I believe there will be other cases where we will need driver-specific
logic to extract the memory content of the segments, e.g. through custom
hardware sequences or non-mmio reads.

To support this I think we should extend the struct rproc_dump_segment
to carry an optional "dump" function that if specified will be used
instead of the memcpy in rproc_coredump(). Drivers can then for each
segment specify this function, if needed.

Through some restructuring in the msa driver and your patch you should
be able to implement this using such a mechanism instead - and it would
be useful to these other cases as well.

PS. I hope we can get away from some of the conditionals in your patch
through some restructuring of the code.

Regards,
Bjorn