linux-kernel - Re: [PATCH v1 1/6] i2c: hpe: Add GXP SoC I2C Controller

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Date:   Mon, 9 Jan 2023 20:23:39 +0000
From:   "Hawkins, Nick" <nick.hawkins@....com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
CC:     "Verdun, Jean-Marie" <verdun@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "lee@...nel.org" <lee@...nel.org>,
        "linux@...linux.org.uk" <linux@...linux.org.uk>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1 1/6] i2c: hpe: Add GXP SoC I2C Controller

> > + GFP_KERNEL);
> > + if (!drvdata)
> > + return -ENOMEM;
> > +
> > + platform_set_drvdata(pdev, drvdata);
> > + drvdata->dev = &pdev->dev;
> > + init_completion(&drvdata->completion);
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + drvdata->base = devm_ioremap_resource(&pdev->dev, res);

> It's one call, not two. Use the respective helper.

Greetings Krzysztof,

Thank you for the feedback. I am in the process of applying your recommended
changes but do have a question on this comment.

I can replace these two lines with:
drvdata->base = devm_platform_ioremap_resource(pdev, 0);

However, I still have a need for the resource "res" here to determine the physical
address of the device here: 

> > + if (IS_ERR(drvdata->base))
> > + return PTR_ERR(drvdata->base);
> > +
> > + drvdata->engine = (res->start & 0xf00) >> 8;
> > + pr_info("%s: i2c engine%d\n", __func__, drvdata->engine);

Hence at some point I believe I will still need to call the "platform_get_resource"
function to accomplish this. Is this acceptable or perhaps you have another
suggestion?

One alternative I thought of was including a property in the device tree node
That specifies which i2c engine this is: hpe,gxp-engine = <1>.

Thank you,

-Nick Hawkins