From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <arnd@arndb.de>
From: Arnd Bergmann <arnd@arndb.de>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Turquette <mturquette@baylibre.com>, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, Andrzej Hajda <a.hajda@samsung.com>, linux-arm-kernel@lists.infradead.org, Tony Prisk <linux@prisktech.co.nz>, Roman Volkov <v1ron@mail.ru>
Subject: Re: [PATCH] clk: vt8500: don't return possibly uninitialized data
Date: Tue, 02 Feb 2016 13:49:56 +0100
Message-ID: <2210116.QsPesySkh0@wuerfel>
In-Reply-To: <20160202011545.GG4848@codeaurora.org>
References: <4790407.6zgSQCdsSB@wuerfel> <20160202011545.GG4848@codeaurora.org>
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List-ID: <linux-clk.vger.kernel.org>

On Monday 01 February 2016 17:15:45 Stephen Boyd wrote:
> My compiler still gets warnings even after this patch is applied.
>=20
> drivers/clk/clk-vt8500.c: In function =E2=80=98wm8750_find_pll_bits=E2=
=80=99:
> drivers/clk/clk-vt8500.c:509:12: warning: =E2=80=98best_div2=E2=80=99=
 may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c:508:12: warning: =E2=80=98best_div1=E2=80=99=
 may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c:507:14: warning: =E2=80=98best_mul=E2=80=99 =
may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c: In function =E2=80=98wm8650_find_pll_bits=E2=
=80=99:
> drivers/clk/clk-vt8500.c:430:12: warning: =E2=80=98best_div2=E2=80=99=
 may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c:429:12: warning: =E2=80=98best_div1=E2=80=99=
 may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c:428:14: warning: =E2=80=98best_mul=E2=80=99 =
may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c: In function =E2=80=98wm8850_find_pll_bits=E2=
=80=99:
> drivers/clk/clk-vt8500.c:560:12: warning: =E2=80=98best_div2=E2=80=99=
 may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c:559:12: warning: =E2=80=98best_div1=E2=80=99=
 may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/clk/clk-vt8500.c:558:14: warning: =E2=80=98best_mul=E2=80=99 =
may be used uninitialized in this function [-Wmaybe-uninitialized]
>=20

I see what you mean now. I checked different gcc versions, and with my =
patch I get
the warnings for 4.6 through 4.9, but not for 5.x.

In general, I tried to only address warnings I still see with newer gcc=
 version,
as they are better about false positives. Do you think it's ok to take =
the
patch as is then? Otherwise we probably have to add fake initialization=
s which
would shut up the warnings but not help with the code quality.

=09Arnd