linux-kernel - Re: [PATCH v2 3/4] Coresight: Add Coresight Control Unit driver

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Message-ID: <ZotaBxRpv29crRHV@jiegan-gv.ap.qualcomm.com>
Date: Mon, 8 Jul 2024 11:16:23 +0800
From: JieGan <quic_jiegan@...cinc.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
CC: Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose
	<suzuki.poulose@....com>,
        Alexander Shishkin
	<alexander.shishkin@...ux.intel.com>,
        Mike Leach <mike.leach@...aro.org>, "Rob Herring" <robh+dt@...nel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        James Clark <james.clark@....com>,
        Jinlong Mao <quic_jinlmao@...cinc.com>, Leo Yan <leo.yan@...aro.org>,
        <coresight@...ts.linaro.org>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        Tingwei Zhang
	<quic_tingweiz@...cinc.com>,
        Yuanfang Zhang <quic_yuanfang@...cinc.com>,
        "Tao
 Zhang" <quic_taozha@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        "Song
 Chai" <quic_songchai@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v2 3/4] Coresight: Add Coresight Control Unit driver

On Fri, Jul 05, 2024 at 11:11:19AM +0200, Krzysztof Kozlowski wrote:
> On 05/07/2024 11:00, Jie Gan wrote:
> > The Coresight Control Unit hosts miscellaneous configuration registers
> > which control various features related to TMC ETR sink.
> > 
> > Based on the trace ID, which is programmed in the related CCU ATID register
> > of a specific ETR, trace data with that trace ID gets into the ETR buffer,
> 
> ....
> 
> > +static int ccu_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct coresight_platform_data *pdata;
> > +	struct ccu_drvdata *drvdata;
> > +	struct coresight_desc desc = { 0 };
> > +	struct resource *res;
> > +
> > +	desc.name = coresight_alloc_device_name(&ccu_devs, dev);
> > +	if (!desc.name)
> > +		return -ENOMEM;
> > +	pdata = coresight_get_platform_data(dev);
> > +	if (IS_ERR(pdata))
> > +		return PTR_ERR(pdata);
> > +	pdev->dev.platform_data = pdata;
> > +
> > +	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> > +	if (!drvdata)
> > +		return -ENOMEM;
> > +	drvdata->dev = &pdev->dev;
> 
> Use stored dev variable.
pdev->dev replaced by dev variable.


> 
> > +	drvdata->atid_offset = 0;
> > +	platform_set_drvdata(pdev, drvdata);
> > +
> > +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ccu-base");
> > +	if (!res)
> > +		return -ENODEV;
> > +	drvdata->pbase = res->start;
> 
> Drop.
Dropped.

> 
> > +
> > +	drvdata->base = devm_ioremap(dev, res->start, resource_size(res));
> 
> Use proper wrapper for this two.
Replaced by:
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
drvdata->base = devm_ioremap_resource(dev, res);

> 
> > +	if (!drvdata->base)
> > +		return -ENOMEM;
> > +
> > +	desc.type = CORESIGHT_DEV_TYPE_HELPER;
> > +	desc.pdata = pdev->dev.platform_data;
> > +	desc.dev = &pdev->dev;
> > +	desc.ops = &ccu_ops;
> > +
> > +	drvdata->csdev = coresight_register(&desc);
> > +	if (IS_ERR(drvdata->csdev))
> > +		return PTR_ERR(drvdata->csdev);
> > +
> > +	dev_dbg(dev, "CCU initialized: %s\n", desc.name);
> 
> Drop.
Dropped.

> 
> > +	return 0;
> > +}
> > +
> > +static void ccu_remove(struct platform_device *pdev)
> > +{
> > +	struct ccu_drvdata *drvdata = platform_get_drvdata(pdev);
> > +
> > +	coresight_unregister(drvdata->csdev);
> > +}
> > +
> > +static const struct of_device_id ccu_match[] = {
> > +	{.compatible = "qcom,coresight-ccu"},
> > +	{}
> > +};
> > +
> > +static struct platform_driver ccu_driver = {
> > +	.probe          = ccu_probe,
> > +	.remove         = ccu_remove,
> > +	.driver         = {
> > +		.name   = "coresight-ccu",
> > +		.of_match_table = ccu_match,
> > +		.suppress_bind_attrs = true,
> 
> Why?
Sorry, I dont get the point here.
We dont need automatic bind/unbind, so the suppress_bind_attrs sets to true.
We need configure some settings before we register the device.

> 
> > +	},
> > +};
> > +
> > +static int __init ccu_init(void)
> > +{
> > +	return platform_driver_register(&ccu_driver);
> > +}
> > +module_init(ccu_init);
> > +
> > +static void __exit ccu_exit(void)
> > +{
> > +	platform_driver_unregister(&ccu_driver);
> > +}
> > +module_exit(ccu_exit);
> 
> Why this is not just module platform driver?
Replaced by module_platform_driver(ccu_driver);

> 
> Best regards,
> Krzysztof
> 


Thanks,
Jie