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Date: Mon, 5 Sep 2016 08:44:41 +0200
From: Thierry Reding <thierry.reding@gmail.com>
To: Brian Norris <briannorris@chromium.org>
Cc: linux-kernel@vger.kernel.org,
        Brian Norris <computersforpeace@gmail.com>, linux-pwm@vger.kernel.org,
        Javier Martinez Canillas <javier@osg.samsung.com>,
        Enric Balletbo <enric.balletbo@collabora.co.uk>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Gwendal Grignou <gwendal@chromium.org>,
        Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH] pwm: cros_ec: add __packed to prevent padding
Message-ID: <20160905064441.GD3532@ulmo.ba.sec>
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On Tue, Jul 26, 2016 at 11:22:13AM -0700, Brian Norris wrote:
> While the particular usage in question is likely safe (struct
> cros_ec_command is 32-bit aligned, followed by <=3D32-bit fields), it's
> been suggested this is not a great pattern to follow for the general
> case -- for example, if we follow a 'struct cros_ec_command' (which is
> 32-bit- but not 64-bit-aligned) with a struct that starts with a 64-bit
> type (e.g., u64), the compiler may add padding.
>=20
> Let's add __packed, to inform the compiler of our true intention -- to
> have no padding between these struct elements -- and to future proof for
> any refactorings that might occur.
>=20
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> Hi Thierry,
>=20
> I don't know of any bugs directly resolved by this patch, so take it for
> v4.8/v4.9 at your discretion.
>=20
>  drivers/pwm/pwm-cros-ec.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied, thanks.

Thierry

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