linux-kernel - Re: [PATCH v7 1/2] hwmon: (asus_wmi_ec

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Message-ID: <CAHp75Ve6q7fkJdLjZaxGe9jKASv72eExJAGWbT8fFWEUAwgweA@mail.gmail.com>
Date:   Fri, 15 Oct 2021 21:04:38 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Eugene Shalygin <eugene.shalygin@...il.com>
Cc:     Denis Pauk <pauk.denis@...il.com>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        thomas@...ssschuh.net, Tor Vic <torvic9@...lbox.org>,
        Oleksandr Natalenko <oleksandr@...alenko.name>,
        kernel test robot <lkp@...el.com>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org,
        Linux Documentation List <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 1/2] hwmon: (asus_wmi_ec_sensors) Support B550 Asus WMI.

On Fri, Oct 15, 2021 at 5:49 PM Eugene Shalygin
<eugene.shalygin@...il.com> wrote:
> On Fri, 15 Oct 2021 at 16:37, Andy Shevchenko <andy.shevchenko@...il.com> wrote:

...

> > I didn't get it. If there is a strong endianess expected the parameter
> > should be __le16 or __be16, moreover it seems it missed the const
> > qualifier. Any preparatory stuff should be done in the
> > asus_wmi_ec_make_block_read_query() which prepares the input buffer,
> > doesn't it?
>
> We need to produce and parse a, roughly speaking, hex-BSTR to pass it
> to the WMI function (save for its size parameter of 16 bits instead of
> 32 for the BSTR). bin/hex conversion functions accept/output UTF-8
> strings and thus require an intermediate buffer and additional utf-8
> <-> utf-16 conversion. Do you insist that a loop with a stride of 4 is
> a homegrown library already?

The code deserves a very good comment. And even if you want to keep
functionality, replace homegrown library calls.

...

> > > > What's the point of calling acpi_os_free(obj) when you already know it's NULL?
> > >
> > > The case when obj->type != ACPI_TYPE_BUFFER
> >
> > Read my comment again, please.
>
> I did it twice already and still can't understand. The WMI method can
> return a string, for example, which is an error for our code, but the
> buffer needs to be freed.

You cut the context, but I think I meant

if (!obj)
  return -ENOMEM;
if (!obj->...) {
  free();
  return -EIO;
}

-- 
With Best Regards,
Andy Shevchenko