linux-kernel - Re: [PATCH v2 6/6] drivers: remoteproc: Add Xilinx r5 remoteproc driver

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Message-ID: <ab9e009a-5e35-ae49-2c8e-65be6ba36d7f@metafoo.de>
Date:   Mon, 13 Dec 2021 12:08:33 +0100
From:   Lars-Peter Clausen <lars@...afoo.de>
To:     Tanmay Shah <tanmay.shah@...inx.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michal Simek <michal.simek@...inx.com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Ben Levinsky <ben.levinsky@...inx.com>,
        Bill Mills <bill.mills@...aro.org>,
        Sergei Korneichuk <sergei.korneichuk@...inx.com>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 6/6] drivers: remoteproc: Add Xilinx r5 remoteproc
 driver

On 11/23/21 7:20 AM, Tanmay Shah wrote:
> [...]
> +/*
> + * zynqmp_r5_rproc_mem_map
> + * @rproc: single R5 core's corresponding rproc instance
> + * @mem: mem entry to map
> + *
> + * Callback to map va for memory-region's carveout.
> + *
> + * return 0 on success, otherwise non-zero value on failure
> + */
> +static int zynqmp_r5_rproc_mem_map(struct rproc *rproc,
> +				   struct rproc_mem_entry *mem)
> +{
> +	void __iomem *va;
> +
> +	va = ioremap_wc(mem->dma, mem->len);

Since you want normal memory and not IO memory a better choice might be 
memremap() with MEMREMAP_WC. Internally memremap() will call 
ioremap_wc(), but this will make the intention clear and you do not have 
to deal with the __iomem type cast.

> +	if (IS_ERR_OR_NULL(va))
> +		return -ENOMEM;
> +
> +	mem->va = (void *)va;
> +
> +	return 0;
> +}
> [...]
>
> +static int add_tcm_banks(struct rproc *rproc)
> +{
> +	struct device *dev;
> +	struct platform_device *parent_pdev;
> +	struct zynqmp_r5_cluster *cluster;
> +	struct zynqmp_r5_core *r5_core;
> +
> +	r5_core = (struct zynqmp_r5_core *)rproc->priv;
> +	if (!r5_core)
> +		return -EINVAL;
> +
> +	dev = r5_core->dev;
> +	if (!dev) {
> +		pr_err("r5 core device unavailable\n");
> +		return -ENODEV;
> +	}
> +
> +	parent_pdev = to_platform_device(dev->parent);
> +	if (!parent_pdev) {
> +		dev_err(dev, "parent platform dev unavailable\n");
> +		return -ENODEV;
> +	}
> +
> +	cluster = platform_get_drvdata(parent_pdev);

You could just use dev_get_drvdata() without having to cast back to the 
platform_device first.


> +	if (!cluster) {
> +		dev_err(&parent_pdev->dev, "Invalid driver data\n");
> +		return -EINVAL;
> +	}
> +
> +	if (cluster->mode == SPLIT_MODE)
> +		return add_tcm_carveout_split_mode(rproc);
> +	else if (cluster->mode == LOCKSTEP_MODE)
> +		return add_tcm_carveout_lockstep_mode(rproc);
> +
> +	dev_err(cluster->dev, "invalid cluster mode\n");
> +	return -EINVAL;
> +}
> +
> [...]
> +
> +static struct rproc_ops zynqmp_r5_rproc_ops = {
const
> +	.start		= zynqmp_r5_rproc_start,
> +	.stop		= zynqmp_r5_rproc_stop,
> +	.load		= rproc_elf_load_segments,
> +	.parse_fw	= zynqmp_r5_parse_fw,
> +	.find_loaded_rsc_table = rproc_elf_find_loaded_rsc_table,
> +	.sanity_check	= rproc_elf_sanity_check,
> +	.get_boot_addr	= rproc_elf_get_boot_addr,
> +};
> [....]
> +static int zynqmp_r5_get_mem_region_node(struct zynqmp_r5_core *r5_core)
> +{
> [...]
> +
> +	for (i = 0; i < res_mem_count; i++) {
> +		rmem_np = of_parse_phandle(np, "memory-region", i);
> +		if (!rmem_np)
> +			return -EINVAL;
> +
> +		rmem = of_reserved_mem_lookup(rmem_np);
> +		if (!rmem) {
> +			of_node_put(rmem_np);
> +			return -EINVAL;
> +		}
> +
> +		memcpy(&r5_core->res_mem[i], rmem,
> +		       sizeof(struct reserved_mem));

r5_core->res_mem[i] = *mem;

This will give you proper type checking and is also a bit shorter.

> +		of_node_put(rmem_np);
> +	}
> +
> +	r5_core->res_mem_count = res_mem_count;
> +
> +	return 0;
> +}
> [...]
> +
> +static int zynqmp_r5_cluster_init(struct zynqmp_r5_cluster *cluster)
> +{
> [...]
> +
>
> +	i = 0;
> +	for_each_available_child_of_node(dev_node, child) {
> +		child_pdev = of_find_device_by_node(child);
> +		if (!child_pdev)
A return or a break in a for_each_available_child_of_node() will leak 
the reference to the child node.
> [...]
> +	}
> +
> [...]
> +
> +	return 0;
> +}
> +
> +static void zynqmp_r5_cluster_exit(void *data)
> +{
> +	struct platform_device *pdev = (struct platform_device *)data;
> +
> +	platform_set_drvdata(pdev, NULL);
This is not needed. The device driver core will set drvdata to NULL when 
the device is removed.
> +
> +	pr_info("Exit r5f subsystem driver\n");
This is probably also not needed.
> +}