linux-kernel - Re: [PATCH V7 4/5] platform/x86: Intel PMT Telemetry capability driver

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Date:   Thu, 1 Oct 2020 09:46:26 -0700
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "David E. Box" <david.e.box@...ux.intel.com>,
        Lee Jones <lee.jones@...aro.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        linux-pci <linux-pci@...r.kernel.org>
Subject: Re: [PATCH V7 4/5] platform/x86: Intel PMT Telemetry capability driver

On Thu, Oct 1, 2020 at 9:03 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Thu, Oct 1, 2020 at 4:43 AM David E. Box <david.e.box@...ux.intel.com> wrote:
> >
> > From: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
> >
> > PMT Telemetry is a capability of the Intel Platform Monitoring Technology.
> > The Telemetry capability provides access to device telemetry metrics that
> > provide hardware performance data to users from read-only register spaces.
> >
> > With this driver present the intel_pmt directory can be populated with
> > telem<x> devices. These devices will contain the standard intel_pmt sysfs
> > data and a "telem" binary sysfs attribute which can be used to access the
> > telemetry data.
>
> ...
>
> > +static DEFINE_XARRAY_ALLOC(telem_array);
> > +static struct intel_pmt_namespace pmt_telem_ns = {
> > +       .name = "telem",
> > +       .xa = &telem_array
>
> Leave comma at the end.
>
> > +};
> > +
> > +/*
> > + * driver initialization
> > + */
>
> This is a useless comment.
>
> > +       size = offsetof(struct pmt_telem_priv, entry[pdev->num_resources]);
> > +       priv = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
> > +       if (!priv)
> > +               return -ENOMEM;
>
> Please, use struct_size() from overflow.h instead of custom approach.
>
> ...

So all of the above make sense and can be fixed shortly and pushed as
a v8 for both the telemetry and crashlog drivers.

> > +static struct platform_driver pmt_telem_driver = {
> > +       .driver = {
> > +               .name   = TELEM_DEV_NAME,
>
> I'm not sure I have interpreted this:
>         - Use 'raw' string instead of defines for device names
> correctly. Can you elaborate?

Can you point me to a reference of that? I'm not sure what you are referring to.

> > +       },
> > +       .remove = pmt_telem_remove,
> > +       .probe  = pmt_telem_probe,
> > +};
>
> ...
>
> > +MODULE_ALIAS("platform:" TELEM_DEV_NAME);
>
> Ditto.

This doesn't make sense to me. Are you saying we are expected to use
"pmt_telemetry" everywhere instead of the define? It seems like that
would be much more error prone. It seems like common practice to use
DRV_NAME throughout a driver for these sort of things so if you are
wanting us to rename it to that I am fine with that, but I am not sure
getting rid of the use of a define makes sense.