linux-kernel - Re: [RFC PATCH v2] soc: qcom: rmtfs_mem: Control remoteproc from rmtfs

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Date:   Sun, 21 Oct 2018 13:16:24 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     briannorris@...omium.org, david.brown@...aro.org,
        robh+dt@...nel.org, mark.rutland@....com, andy.gross@...aro.org,
        akdwived@...eaurora.org, clew@...eaurora.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org, linux-arm-msm-owner@...r.kernel.org
Subject: Re: [RFC PATCH v2] soc: qcom: rmtfs_mem: Control remoteproc from
 rmtfs_mem

On Sun 30 Sep 08:56 PDT 2018, Sibi Sankar wrote:

> From: Bjorn Andersson <bjorn.andersson@...aro.org>
> 
> rmtfs_mem provides access to physical storage and is crucial for the
> operation of the Qualcomm modem subsystem.
> 
> The rmtfs_mem implementation must be available before the modem
> subsystem is booted and a solution where the modem remoteproc will
> verify that the rmtfs_mem is available has been discussed in the past.
> But this would not handle the case where the rmtfs_mem provider is
> restarted, which would cause fatal loss of access to the storage device
> for the modem.
> 
> The suggestion is therefore to link the rmtfs_mem to its associated
> remote processor instance and control it based on the availability of
> the rmtfs_mem implementation.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> [sibis: Added qmi lookup for Remote file system service]
> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>

Thanks Sibi,

This looks clean and straight forward, but I think the logic should be
moved into the qcom_q6v5_mss driver itself - as we now only care about
the QMI service being present, not the rmtfs_memory driver.

There's nothing left of my original patch, so please credit yourself as
author of v3.

[..]
> diff --git a/drivers/soc/qcom/rmtfs_mem.c b/drivers/soc/qcom/rmtfs_mem.c
[..]
> @@ -181,6 +217,22 @@ static int qcom_rmtfs_mem_probe(struct platform_device *pdev)
>  	rmtfs_mem->client_id = client_id;
>  	rmtfs_mem->size = rmem->size;
>  
> +	ret = of_property_read_u32(node, "rproc", &rproc_phandle);
> +	if (!ret) {
> +		rmtfs_mem->rproc = rproc_get_by_phandle(rproc_phandle);
> +		if (!rmtfs_mem->rproc)
> +			return -EPROBE_DEFER;
> +	}
> +
> +	ret = qmi_handle_init(&rmtfs_mem->rmtfs_hdl, 0,
> +			      &rmtfs_lookup_ops, NULL);
> +	if (ret < 0)
> +		goto put_rproc;
> +
> +	ret = qmi_add_lookup(&rmtfs_mem->rmtfs_hdl, 14, 0, 0);

The 14 here deserves a define and the whole thing would benefit from a
comment describing the remoteproc's dependency on the RMTFS service
being present.

> +	if (ret < 0)
> +		goto err_release_qmi_handle;
> +
>  	device_initialize(&rmtfs_mem->dev);
>  	rmtfs_mem->dev.parent = &pdev->dev;
>  	rmtfs_mem->dev.groups = qcom_rmtfs_mem_groups;

Looking forward to v3!

Regards,
Bjorn