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([78.42.132.4]) by mrelayeu.kundenserver.de (mreue001) with ESMTPA (Nemesis) id 0LzThi-1ZlUdG0YYk-014nHU; Wed, 16 Mar 2016 21:51:44 +0100 From: Arnd Bergmann To: H Hartley Sweeten Cc: Arnd Bergmann , Ian Abbott , Greg Kroah-Hartman , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] staging/comedi/dt282x: avoid integer overflow warning Date: Wed, 16 Mar 2016 21:51:23 +0100 Message-Id: <1458161501-283680-1-git-send-email-arnd@arndb.de> X-Mailer: git-send-email 2.7.0 X-Provags-ID: V03:K0:ylvCaUXwtG0x7EtLEDNQk5uPrA5+F+1tCl55r3BxtdqkX3NqGmR 1teUcrPY8mtM1ROdqmGp5xUobjYZeRWfJFHNei2ggxi/8ox/BDNUnAmfjz5w/QWUUPlkHTf ZllqcNEj5pJmulc9tbvxP9H3UQetKm5LKzKuFjFaFRr52qADXUvnyxmbOX02eR1mYKS7H4s oEHLb+a/EU2Q6MARlmSvQ== X-UI-Out-Filterresults: notjunk:1; V01:K0:pKXdkkyC16Q=:6lyA+hrndgNznS+tsXARiJ NC17cpLcRv0r+Pk6sFU6sunvyE/bWyPUSDaP47jA8h+9SNkFutMeuTVtl/fIUEZtG9tyo4EoJ bxLtQE47xTNfLPHaQesXPBOeNCrrSnQOMn/UmgU9TgVnTBMWt1XeN/ISyFy8NEdmQjlhY//ao 8HXBDUaniK0vA0Qf8gMtH2HsPfrI/bzt9SHsVa+9HMJsAr46HD+nQ6Hf7GtrJyG4rY8YzqBNd C8QGp7dLFK3E016Hfb4+TrsL4CJ9KkOiQfrrgKMT8rsEupbZhVfoOHWdrwGCGgaHN9vdHOM9K 6jwAJvpE3QcmNeLsDAIpvwwTreorLAkkhMYNUrQUTxbNIdVHZi0bYktvhPggeK/XvDYYey9jw MhJkFk0VrJZX9Zdl3b9NH9SqLI1jfeXe9yPXl7uoOJOur4IY+IUxxgshinODRJkvP589qYNM7 Qeclt3T70HB9Mhit4m/gRxWVq1RcOKRsq9EJJ+t2lMAkrW22ruJPKtqjdzyK8X1jmewWWj1eZ 57actSoJf1K6k+tvVyC5vzxebPyxXDKhMTdt74V8+8to+IUxWUh+j8IuIkjhIL3m4T9Ts20vf 9npUhyenVA+fSiJUsMgl6eZtBYRfJdiko9YACEgTNIyk4iyuofQvO0/uUX4TmMHb5mthXt0fX MKn1r5yCQ9vL2Y8ZyZgimEFUiKIAd9mQy2iq5NPRz1lAusNVVVcVtFWnOeo2FnPkSG+Q= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org gcc-6 warns about passing negative signed integer into swab16() in the dt282x driver: drivers/staging/comedi/drivers/dt282x.c: In function 'dt282x_load_changain': include/uapi/linux/swab.h:14:33: warning: integer overflow in expression [-Woverflow] (((__u16)(x) & (__u16)0xff00U) >> 8))) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~ include/uapi/linux/swab.h:107:2: note: in expansion of macro '___constant_swab16' ___constant_swab16(x) : \ ^~~~~~~~~~~~~~~~~~ include/uapi/linux/byteorder/big_endian.h:34:43: note: in expansion of macro '__swab16' #define __cpu_to_le16(x) ((__force __le16)__swab16((x))) ^~~~~~~~ include/linux/byteorder/generic.h:89:21: note: in expansion of macro '__cpu_to_le16' #define cpu_to_le16 __cpu_to_le16 ^~~~~~~~~~~~~ arch/arm/include/asm/io.h:250:6: note: in expansion of macro 'cpu_to_le16' cpu_to_le16(v),__io(p)); }) ^~~~~~~~~~~ drivers/staging/comedi/drivers/dt282x.c:566:2: note: in expansion of macro 'outw' outw(DT2821_CHANCSR_LLE | DT2821_CHANCSR_NUMB(n), ^~~~ 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. As pointed out by Hartley Sweeten, scripts/checkpatch.pl notices that the shifts here are rather unreadable, though the suggested BIT() macro wouldn't work either. I'm changing it to a hexadecimal notation, which hopefully improves readability. I'm leaving the DT2821_CHANCSR_PRESLA alone because it seems wrong. Signed-off-by: Arnd Bergmann --- v2: also reformat to make checkpatch.pl happy drivers/staging/comedi/drivers/dt282x.c | 72 ++++++++++++++++----------------- 1 file changed, 36 insertions(+), 36 deletions(-) -- 2.7.0 diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c index 40bf00984fa5..991e9f44c18c 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_GS(x) (((x) & 0x3) << 4) -#define DT2821_ADCSR_CHAN(x) (((x) & 0xf) << 0) +#define DT2821_ADCSR_ADERR 0x8000u +#define DT2821_ADCSR_ADCLK 0x0200u +#define DT2821_ADCSR_MUXBUSY 0x0100u +#define DT2821_ADCSR_ADDONE 0x0080u +#define DT2821_ADCSR_IADDONE 0x0040u +#define DT2821_ADCSR_GS(x) (0x0030u & ((x) << 4)) +#define DT2821_ADCSR_CHAN(x) (0x000fu & (x)) #define DT2821_CHANCSR_REG 0x02 -#define DT2821_CHANCSR_LLE (1 << 15) -#define DT2821_CHANCSR_PRESLA(x) (((x) & 0xf) >> 8) -#define DT2821_CHANCSR_NUMB(x) ((((x) - 1) & 0xf) << 0) +#define DT2821_CHANCSR_LLE 0x8000u +#define DT2821_CHANCSR_PRESLA(x) (((x) & 0xf) >> 8) /* always 0? */ +#define DT2821_CHANCSR_NUMB(x) (0x000fu & ((x) - 1)) #define DT2821_ADDAT_REG 0x04 #define DT2821_DACSR_REG 0x06 -#define DT2821_DACSR_DAERR (1 << 15) -#define DT2821_DACSR_YSEL(x) ((x) << 9) -#define DT2821_DACSR_SSEL (1 << 8) -#define DT2821_DACSR_DACRDY (1 << 7) -#define DT2821_DACSR_IDARDY (1 << 6) -#define DT2821_DACSR_DACLK (1 << 5) -#define DT2821_DACSR_HBOE (1 << 1) -#define DT2821_DACSR_LBOE (1 << 0) +#define DT2821_DACSR_DAERR 0x8000u +#define DT2821_DACSR_YSEL(x) (0x7e00u & (x) << 9) +#define DT2821_DACSR_SSEL 0x0100u +#define DT2821_DACSR_DACRDY 0x0080u +#define DT2821_DACSR_IDARDY 0x0040u +#define DT2821_DACSR_DACLK 0x0020u +#define DT2821_DACSR_HBOE 0x0002u +#define DT2821_DACSR_LBOE 0x0001u #define DT2821_DADAT_REG 0x08 #define DT2821_DIODAT_REG 0x0a #define DT2821_SUPCSR_REG 0x0c -#define DT2821_SUPCSR_DMAD (1 << 15) -#define DT2821_SUPCSR_ERRINTEN (1 << 14) -#define DT2821_SUPCSR_CLRDMADNE (1 << 13) -#define DT2821_SUPCSR_DDMA (1 << 12) -#define DT2821_SUPCSR_DS_PIO (0 << 10) -#define DT2821_SUPCSR_DS_AD_CLK (1 << 10) -#define DT2821_SUPCSR_DS_DA_CLK (2 << 10) -#define DT2821_SUPCSR_DS_AD_TRIG (3 << 10) -#define DT2821_SUPCSR_BUFFB (1 << 9) -#define DT2821_SUPCSR_SCDN (1 << 8) -#define DT2821_SUPCSR_DACON (1 << 7) -#define DT2821_SUPCSR_ADCINIT (1 << 6) -#define DT2821_SUPCSR_DACINIT (1 << 5) -#define DT2821_SUPCSR_PRLD (1 << 4) -#define DT2821_SUPCSR_STRIG (1 << 3) -#define DT2821_SUPCSR_XTRIG (1 << 2) -#define DT2821_SUPCSR_XCLK (1 << 1) -#define DT2821_SUPCSR_BDINIT (1 << 0) +#define DT2821_SUPCSR_DMAD 0x8000u +#define DT2821_SUPCSR_ERRINTEN 0x4000u +#define DT2821_SUPCSR_CLRDMADNE 0x2000u +#define DT2821_SUPCSR_DDMA 0x1000u +#define DT2821_SUPCSR_DS_PIO (0x0c00u & (0u << 10)) +#define DT2821_SUPCSR_DS_AD_CLK (0x0c00u & (1u << 10)) +#define DT2821_SUPCSR_DS_DA_CLK (0x0c00u & (2u << 10)) +#define DT2821_SUPCSR_DS_AD_TRIG (0x0c00u & (3u << 10)) +#define DT2821_SUPCSR_BUFFB 0x0200u +#define DT2821_SUPCSR_SCDN 0x0100u +#define DT2821_SUPCSR_DACON 0x0080u +#define DT2821_SUPCSR_ADCINIT 0x0040u +#define DT2821_SUPCSR_DACINIT 0x0020u +#define DT2821_SUPCSR_PRLD 0x0010u +#define DT2821_SUPCSR_STRIG 0x0008u +#define DT2821_SUPCSR_XTRIG 0x0004u +#define DT2821_SUPCSR_XCLK 0x0002u +#define DT2821_SUPCSR_BDINIT 0x0001u #define DT2821_TMRCTR_REG 0x0e static const struct comedi_lrange range_dt282x_ai_lo_bipolar = {