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.
Signed-off-by: Arnd Bergmann <[email protected]>
---
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)
+#define DT2821_ADCSR_ADCLK (1u << 9)
+#define DT2821_ADCSR_MUXBUSY (1u << 8)
+#define DT2821_ADCSR_ADDONE (1u << 7)
+#define DT2821_ADCSR_IADDONE (1u << 6)
#define DT2821_ADCSR_GS(x) (((x) & 0x3) << 4)
#define DT2821_ADCSR_CHAN(x) (((x) & 0xf) << 0)
#define DT2821_CHANCSR_REG 0x02
-#define DT2821_CHANCSR_LLE (1 << 15)
+#define DT2821_CHANCSR_LLE (1u << 15)
#define DT2821_CHANCSR_PRESLA(x) (((x) & 0xf) >> 8)
#define DT2821_CHANCSR_NUMB(x) ((((x) - 1) & 0xf) << 0)
#define DT2821_ADDAT_REG 0x04
#define DT2821_DACSR_REG 0x06
-#define DT2821_DACSR_DAERR (1 << 15)
+#define DT2821_DACSR_DAERR (1u << 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_SSEL (1u << 8)
+#define DT2821_DACSR_DACRDY (1u << 7)
+#define DT2821_DACSR_IDARDY (1u << 6)
+#define DT2821_DACSR_DACLK (1u << 5)
+#define DT2821_DACSR_HBOE (1u << 1)
+#define DT2821_DACSR_LBOE (1u << 0)
#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 (1u << 15)
+#define DT2821_SUPCSR_ERRINTEN (1u << 14)
+#define DT2821_SUPCSR_CLRDMADNE (1u << 13)
+#define DT2821_SUPCSR_DDMA (1u << 12)
+#define DT2821_SUPCSR_DS_PIO (0u << 10)
+#define DT2821_SUPCSR_DS_AD_CLK (1u << 10)
+#define DT2821_SUPCSR_DS_DA_CLK (2u << 10)
+#define DT2821_SUPCSR_DS_AD_TRIG (3u << 10)
+#define DT2821_SUPCSR_BUFFB (1u << 9)
+#define DT2821_SUPCSR_SCDN (1u << 8)
+#define DT2821_SUPCSR_DACON (1u << 7)
+#define DT2821_SUPCSR_ADCINIT (1u << 6)
+#define DT2821_SUPCSR_DACINIT (1u << 5)
+#define DT2821_SUPCSR_PRLD (1u << 4)
+#define DT2821_SUPCSR_STRIG (1u << 3)
+#define DT2821_SUPCSR_XTRIG (1u << 2)
+#define DT2821_SUPCSR_XCLK (1u << 1)
+#define DT2821_SUPCSR_BDINIT (1u << 0)
#define DT2821_TMRCTR_REG 0x0e
static const struct comedi_lrange range_dt282x_ai_lo_bipolar = {
--
2.7.0
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 <[email protected]>
> ---
> 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
On Tuesday 15 March 2016 21:35:40 Hartley Sweeten wrote:
> 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 <[email protected]>
> > ---
> > 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.
Yes, but it won't work for the ones that have more than one bit:
#define DT2821_SUPCSR_DS_AD_TRIG (3 << 10)
I considered using BIT() but decided against it for consistency.
Arnd
On Tuesday, March 15, 2016 2:50 PM, Arnd Bergmann wrote:
> On Tuesday 15 March 2016 21:35:40 Hartley Sweeten wrote:
>> 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 <[email protected]>
>>> ---
>>> 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.
>
> Yes, but it won't work for the ones that have more than one bit:
>
> #define DT2821_SUPCSR_DS_AD_TRIG (3 << 10)
Use a helper macro for those bits:
#define DT2821_SUPCSR_DS(x) (((x) & 0x3) << 10)
#define DT2821_SUPCSR_DS_PIO DT2821_SUPCSR_DS(0)
#define DT2821_SUPCSR_DS_AD_CLK DT2821_SUPCSR_DS(1)
#define DT2821_SUPCSR_DS_DA_CLK DT2821_SUPCSR_DS(2)
#define DT2821_SUPCSR_DS_AD_TRIG DT2821_SUPCSR_DS(3)
> I considered using BIT() but decided against it for consistency.
Your change may fix the gcc-6 issue but it doesn't fix the 28 checkpatch.pl
issues:
CHECK: Prefer using the BIT macro
Regards,
Hartley
On Wednesday 16 March 2016 17:04:15 Hartley Sweeten wrote:
> > #define DT2821_SUPCSR_DS_AD_TRIG (3 << 10)
>
> Use a helper macro for those bits:
>
> #define DT2821_SUPCSR_DS(x) (((x) & 0x3) << 10)
> #define DT2821_SUPCSR_DS_PIO DT2821_SUPCSR_DS(0)
> #define DT2821_SUPCSR_DS_AD_CLK DT2821_SUPCSR_DS(1)
> #define DT2821_SUPCSR_DS_DA_CLK DT2821_SUPCSR_DS(2)
> #define DT2821_SUPCSR_DS_AD_TRIG DT2821_SUPCSR_DS(3)
>
> > I considered using BIT() but decided against it for consistency.
>
> Your change may fix the gcc-6 issue but it doesn't fix the 28 checkpatch.pl
> issues:
> CHECK: Prefer using the BIT macro
I sent a new version now, and found a better solution that avoids
using BIT().
Arnd