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From: Hartley Sweeten <HartleyS@visionengravers.com>
To: Arnd Bergmann <arnd@arndb.de>, Ian Abbott <abbotti@mev.co.uk>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
CC: Amitoj Kaur Chawla <amitoj1606@gmail.com>,
        Bhaktipriya Shridhar <bhaktipriya96@gmail.com>,
        "devel@driverdev.osuosl.org" <devel@driverdev.osuosl.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] staging/comedi/dt282x: avoid integer overflow warning
Thread-Topic: [PATCH] staging/comedi/dt282x: avoid integer overflow warning
Thread-Index: AQHRfkOqoOuQ0v17NkiW6jbPL4yfgZ9bCEJQ
Date: Tue, 15 Mar 2016 21:35:40 +0000
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On Monday, March 14, 2016 3:48 PM, Arnd Bergmann wrote:
> gcc-6 warns about passing negative signed integer into swab16()
> in the dt282x driver:

<snip>

> The warning makes sense, though the code is correct as far as I
> can tell.
>
> This disambiguates the operation by making the constant expressions
> we pass here explicitly 'unsigned', which helps to avoid the warning.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/staging/comedi/drivers/dt282x.c | 62 ++++++++++++++++-----------------
>  1 file changed, 31 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
> index 40bf00984fa5..d4d45c759c62 100644
> --- a/drivers/staging/comedi/drivers/dt282x.c
> +++ b/drivers/staging/comedi/drivers/dt282x.c
> @@ -69,48 +69,48 @@
>   * Register map
>   */
>  #define DT2821_ADCSR_REG		0x00
> -#define DT2821_ADCSR_ADERR		(1 << 15)
> -#define DT2821_ADCSR_ADCLK		(1 << 9)
> -#define DT2821_ADCSR_MUXBUSY		(1 << 8)
> -#define DT2821_ADCSR_ADDONE		(1 << 7)
> -#define DT2821_ADCSR_IADDONE		(1 << 6)
> +#define DT2821_ADCSR_ADERR		(1u << 15)

Changing all of these to use the BIT() macro should also avoid the warning.

Hartley