Re: [PATCH v4 05/11] clk: Introduce clk-tps68470 driver

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Hans de Goede <hdegoede@redhat.com>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Mark Gross <markgross@kernel.org>,
	Andy Shevchenko <andy@infradead.org>,
	Wolfram Sang <wsa@the-dreams.de>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Daniel Scally <djrscally@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>, Len Brown <lenb@kernel.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Platform Driver <platform-driver-x86@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-i2c <linux-i2c@vger.kernel.org>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Kate Hsuan <hpa@redhat.com>,
	Linux Media Mailing List <linux-media@vger.kernel.org>,
	linux-clk <linux-clk@vger.kernel.org>
Subject: Re: [PATCH v4 05/11] clk: Introduce clk-tps68470 driver
Date: Mon, 1 Nov 2021 12:42:37 +0200	[thread overview]
Message-ID: <CAHp75VfUq+DZk_u5Wsyr5nnibbe+WrYDyhvCU22=4Pog06DgHg@mail.gmail.com> (raw)
In-Reply-To: <ff8c8418-8e73-f949-3734-c0e2e109f554@redhat.com>

On Mon, Nov 1, 2021 at 12:27 PM Hans de Goede <hdegoede@redhat.com> wrote:
> On 10/25/21 13:24, Andy Shevchenko wrote:
> > On Mon, Oct 25, 2021 at 12:42 PM Hans de Goede <hdegoede@redhat.com> wrote:

...

> >> +       for (i = 0; i < ARRAY_SIZE(clk_freqs); i++) {
> >> +               diff = clk_freqs[i].freq - rate;
> >> +               if (diff == 0)
> >> +                       return i;
> >
> >> +               diff = abs(diff);
> >
> > This needs a comment why higher (lower) frequency is okay.
>
> This function is called in 2 places:
>
> 1. From tps68470_clk_round_rate(), where higher/lower clearly is ok,
> (see the function name) so no comment needed.
>
> 2. From tps68470_clk_set_rate() where it is NOT ok and this is
> enforced in the caller:
>
>         unsigned int idx = tps68470_clk_cfg_lookup(rate);
>
>         if (rate != clk_freqs[idx].freq)
>                 return -EINVAL;
>
> This is not easy to describe in a comment, while being obvious
> if someone looking at this actually looks at the callers.

Hmm... but try your best. :-)

While at it, recently I have learned about util_macros.h. Any use of it here?
Or amending it there and re-using it here?

> >> +               if (diff < best_diff) {
> >> +                       best_diff = diff;
> >> +                       best_idx = i;
> >> +               }
> >> +       }

-- 
With Best Regards,
Andy Shevchenko