Re: [RFC PATCH v5 2/6] interconnect: Add generic interconnect driver for Exynos SoCs

[Sylwester Nawrocki]

Hi Georgi,

On 01.07.2020 14:50, Georgi Djakov wrote:
> Thanks for the patch and apologies for the delayed reply.

Thanks, no problem. It's actually just in time as I put that patchset
aside for a while and was just about to post an update.
 
> On 5/29/20 19:31, Sylwester Nawrocki wrote:
>> This patch adds a generic interconnect driver for Exynos SoCs in order
>> to provide interconnect functionality for each "samsung,exynos-bus"
>> compatible device.
>>
>> The SoC topology is a graph (or more specifically, a tree) and its
>> edges are specified using the 'samsung,interconnect-parent' in the
>> DT. Due to unspecified relative probing order, -EPROBE_DEFER may be
>> propagated to ensure that the parent is probed before its children.
>>
>> Each bus is now an interconnect provider and an interconnect node as
>> well (cf. Documentation/interconnect/interconnect.rst), i.e. every bus
>> registers itself as a node. Node IDs are not hardcoded but rather
>> assigned dynamically at runtime. This approach allows for using this
>> driver with various Exynos SoCs.
>>
>> Frequencies requested via the interconnect API for a given node are
>> propagated to devfreq using dev_pm_qos_update_request(). Please note
>> that it is not an error when CONFIG_INTERCONNECT is 'n', in which
>> case all interconnect API functions are no-op.
>>
>> Signed-off-by: Artur ÅwigoÅ <a.swigon@xxxxxxxxxxx>
>> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>

>> +static struct icc_node *exynos_icc_get_parent(struct device_node *np)
>> +{
>> +	struct of_phandle_args args;
>> +	int num, ret;
>> +
>> +	num = of_count_phandle_with_args(np, "samsung,interconnect-parent",
>> +					"#interconnect-cells");
>> +	if (num != 1)
>> +		return NULL; /* parent nodes are optional */
>> +
>> +	ret = of_parse_phandle_with_args(np, "samsung,interconnect-parent",
>> +					"#interconnect-cells", 0, &args);
>> +	if (ret < 0)
>> +		return ERR_PTR(ret);
>> +
>> +	of_node_put(args.np);
>> +
>> +	return of_icc_get_from_provider(&args);
>> +}
>> +
>> +
> 
> Nit: multiple blank lines

Fixed.

> [..]
>> +static struct icc_node *exynos_generic_icc_xlate(struct of_phandle_args *spec,
>> +						 void *data)
>> +{
>> +	struct exynos_icc_priv *priv = data;
>> +
>> +	if (spec->np != priv->dev->parent->of_node)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	return priv->node;
>> +}
>> +
>> +static int exynos_generic_icc_remove(struct platform_device *pdev)
>> +{
>> +	struct exynos_icc_priv *priv = platform_get_drvdata(pdev);
>> +	struct icc_node *parent_node, *node = priv->node;
>> +
>> +	parent_node = exynos_icc_get_parent(priv->dev->parent->of_node);
>> +	if (parent_node && !IS_ERR(parent_node))
> 
> Nit: !IS_ERR_OR_NULL?

It was left on purpose that way but I changed it now to IS_ERR_OR_NULL.

>> +		icc_link_destroy(node, parent_node);
>> +
>> +	icc_nodes_remove(&priv->provider);
>> +	icc_provider_del(&priv->provider);
>> +
>> +	return 0;
>> +}
>> +
>> +static int exynos_generic_icc_probe(struct platform_device *pdev)
>> +{
>> +	struct device *bus_dev = pdev->dev.parent;
>> +	struct exynos_icc_priv *priv;
>> +	struct icc_provider *provider;
>> +	struct icc_node *icc_node, *icc_parent_node;
>> +	int ret;
>> +
>> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->dev = &pdev->dev;
>> +	platform_set_drvdata(pdev, priv);
>> +
>> +	provider = &priv->provider;
>> +
>> +	provider->set = exynos_generic_icc_set;
>> +	provider->aggregate = icc_std_aggregate;
>> +	provider->xlate = exynos_generic_icc_xlate;
>> +	provider->dev = bus_dev;
>> +	provider->inter_set = true;
>> +	provider->data = priv;
>> +
>> +	ret = icc_provider_add(provider);
> 
> Nit: Maybe it would be better to move this after the node is created. The
> idea is to create the nodes first and add the provider when the topology is
> populated. It's fine either way here, but i am planning to change this in
> some of the existing provider drivers.

OK, it makes the clean up path a bit less straightforward. And still we need 
to register the provider before calling icc_node_add().
I made a change as below.

--------------8<------------------
@@ -124,14 +123,14 @@ static int exynos_generic_icc_probe(struct platform_device *pdev)
 	provider->inter_set = true;
 	provider->data = priv;
 
+	icc_node = icc_node_create(pdev->id);
+	if (IS_ERR(icc_node))
+		return PTR_ERR(icc_node);
+
 	ret = icc_provider_add(provider);
-	if (ret < 0)
+	if (ret < 0) {
+		icc_node_destroy(icc_node->id);
 		return ret;
-
-	icc_node = icc_node_create(pdev->id);
-	if (IS_ERR(icc_node)) {
-		ret = PTR_ERR(icc_node);
-		goto err_prov_del;
 	}
 
 	priv->node = icc_node;
@@ -171,9 +170,7 @@ static int exynos_generic_icc_probe(struct platform_device *pdev)
 		icc_link_destroy(icc_node, icc_parent_node);
 err_node_del:
 	icc_nodes_remove(provider);
-err_prov_del:
 	icc_provider_del(provider);
-
 	return ret;
 }
--------------8<------------------


>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	icc_node = icc_node_create(pdev->id);
>> +	if (IS_ERR(icc_node)) {
>> +		ret = PTR_ERR(icc_node);
>> +		goto err_prov_del;
>> +	}
>> +
>> +	priv->node = icc_node;
>> +	icc_node->name = bus_dev->of_node->name;
>> +	icc_node->data = priv;
>> +	icc_node_add(icc_node, provider);
>> +
>> +	icc_parent_node = exynos_icc_get_parent(bus_dev->of_node);
>> +	if (IS_ERR(icc_parent_node)) {
>> +		ret = PTR_ERR(icc_parent_node);
>> +		goto err_node_del;
>> +	}
>> +	if (icc_parent_node) {
>> +		ret = icc_link_create(icc_node, icc_parent_node->id);
>> +		if (ret < 0)
>> +			goto err_node_del;
>> +	}
>> +
>> +	/*
>> +	 * Register a PM QoS request for the bus device for which also devfreq
>> +	 * functionality is registered.
>> +	 */
>> +	ret = dev_pm_qos_add_request(bus_dev, &priv->qos_req,
>> +				     DEV_PM_QOS_MIN_FREQUENCY, 0);
>> +	if (ret < 0)
>> +		goto err_link_destroy;
>> +
>> +	return 0;
>> +
>> +err_link_destroy:
>> +	if (icc_parent_node)
>> +		icc_link_destroy(icc_node, icc_parent_node);
>> +err_node_del:
>> +	icc_nodes_remove(provider);
>> +err_prov_del:
>> +	icc_provider_del(provider);
>> +
>> +	return ret;
>> +}

> All looks good to me, but it seems that the patch-set is not on
> Rob's radar currently, so please re-send and CC the DT mailing list.

Thanks, indeed I missed some mailing list when posting. I will make sure
Rob and DT ML list is on Cc, especially that I have added new "bus-width" 
property in v6.

-- 
Regards,
Sylwester