linux-kernel - Re: [PATCH v15 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver

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Message-ID: <20200921221206.GA296714@xaphan>
Date:   Mon, 21 Sep 2020 17:12:06 -0500
From:   Michael Auchter <michael.auchter@...com>
To:     Ben Levinsky <ben.levinsky@...inx.com>
Cc:     sunnyliangjy@...il.com, punit1.agrawal@...hiba.co.jp,
        stefanos@...inx.com, michals@...inx.com,
        devicetree@...r.kernel.org, mathieu.poirier@...aro.org,
        emooring@...inx.com, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, robh+dt@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        Wendy Liang <wendy.liang@...inx.com>,
        Michal Simek <michal.simek@...inx.com>,
        Ed Mooring <ed.mooring@...inx.com>, Jason Wu <j.wu@...inx.com>
Subject: Re: [PATCH v15 5/5] remoteproc: Add initial zynqmp R5 remoteproc driver

Hey Ben,

Thanks for sending out the new series, this patchset is functional for
booting both R5 0 and R5 1 in split mode.

A few comments below, still working my way through the rest of the code
though now that this works.

On Mon, Sep 21, 2020 at 09:14:06AM -0700, Ben Levinsky wrote:
<...>
> +static int zynqmp_r5_remoteproc_probe(struct platform_device *pdev)
> +{
> +	int ret, i = 0;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *nc;
> +
> +	rpu_mode =  of_get_property(dev->of_node, "lockstep-mode", NULL) ?
> +		    PM_RPU_MODE_LOCKSTEP : PM_RPU_MODE_SPLIT;

Extra whitespace, and of_property_read_bool would read a bit nicer here
(does the same thing in the end, though).

Since rpu_mode is only used here and in r5_set_mode, I think it'd be
better to plumb it through zynqmp_r5_probe instead of making it global
in this file.

> +
> +	dev_dbg(dev, "RPU configuration: %s\n",
> +		rpu_mode == PM_RPU_MODE_LOCKSTEP ? "lockstep" : "split");
> +
> +	for_each_available_child_of_node(dev->of_node, nc) {
> +		/*
> +		 * if 2 RPUs provided but one is lockstep, then we have an
> +		 * invalid configuration.
> +		 */
> +		if (i > 0 && rpu_mode == PM_RPU_MODE_LOCKSTEP)
> +			return -EINVAL;
> +
> +		/* only call zynqmp_r5_probe if proper # of rpu's */
> +		ret = (i < MAX_RPROCS) ? zynqmp_r5_probe(&rpus[i], pdev, nc) :
> +					 -EINVAL;
> +		dev_dbg(dev, "%s to probe rpu %pOF\n",
> +			ret ? "Failed" : "Able",
> +			nc);

It'd be cleaner to check the child node count before the loop:

	rpu_nodes = of_get_available_child_count(nc)
	if ((rpu_mode == PM_RPU_MODE_LOCKSTEP && rpu_nodes != 1) || rpu_nodes > 2)
		return -EINVAL;

> +
> +		if (ret)
> +			return ret;
> +
> +		i++;
> +	}
> +
> +	return 0;
> +}
> +
> +static int zynqmp_r5_remoteproc_remove(struct platform_device *pdev)
> +{
> +	int i;
> +
> +	for (i = 0; i < MAX_RPROCS; i++) {
> +		struct zynqmp_r5_pdata *pdata = &rpus[i];
> +		struct rproc *rproc;
> +
> +		/* only do clean up for pdata with active rpu */
> +		if (pdata->pnode_id == 0)
> +			continue;

This seems like a bit of a hack, resulting from the use of a static
array for holding the zynqmp_r5_pdata for each rpu.

Consider allocating zynqmp_r5_pdata in zynqmp_r5_probe, and adding each
instance to a linked-list at file scope. 
	- memory is only allocated RPUs actually in use
	- no need for this pnode_id == 0 hack
	- MAX_RPROCS can be eliminated, just traverse that list in
	  remove
	- No reuse of the pdata across probe/removes, so all of the e.g.
	  condtionals below ("if (rproc)") and NULL assignments can be
	  eliminated.

> +
> +		rproc = pdata->rproc;
> +		if (rproc) {
> +			rproc_del(rproc);
> +			rproc_free(rproc);
> +			pdata->rproc = NULL;
> +		}
> +		if (pdata->tx_chan) {
> +			mbox_free_channel(pdata->tx_chan);
> +			pdata->tx_chan = NULL;
> +		}
> +		if (pdata->rx_chan) {
> +			mbox_free_channel(pdata->rx_chan);
> +			pdata->rx_chan = NULL;
> +		}
> +		if (&(&pdata->dev)->dma_pools)
> +			device_unregister(&pdata->dev);

The condition here looks very wrong to me, as it will always be true.
What is this trying to achieve?

> +	}
> +
> +	return 0;
> +}
> +
> +/* Match table for OF platform binding */
> +static const struct of_device_id zynqmp_r5_remoteproc_match[] = {
> +	{ .compatible = "xlnx,zynqmp-r5-remoteproc-1.0", },
> +	{ /* end of list */ },
> +};
> +MODULE_DEVICE_TABLE(of, zynqmp_r5_remoteproc_match);
> +
> +static struct platform_driver zynqmp_r5_remoteproc_driver = {
> +	.probe = zynqmp_r5_remoteproc_probe,
> +	.remove = zynqmp_r5_remoteproc_remove,
> +	.driver = {
> +		.name = "zynqmp_r5_remoteproc",
> +		.of_match_table = zynqmp_r5_remoteproc_match,
> +	},
> +};
> +module_platform_driver(zynqmp_r5_remoteproc_driver);
> +
> +MODULE_AUTHOR("Ben Levinsky <ben.levinsky@...inx.com>");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.17.1
> 

Thanks,
 Michael