Clang warns:
sound/soc/codecs/src4xxx.c:280:3: error: variable 'd' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
default:
^~~~~~~
sound/soc/codecs/src4xxx.c:298:59: note: uninitialized use occurs here
ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_11, d);
^
sound/soc/codecs/src4xxx.c:223:20: note: initialize the variable 'd' to silence this warning
int val, pj, jd, d;
^
= 0
sound/soc/codecs/src4xxx.c:280:3: error: variable 'jd' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
default:
^~~~~~~
sound/soc/codecs/src4xxx.c:293:59: note: uninitialized use occurs here
ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_10, jd);
^~
sound/soc/codecs/src4xxx.c:223:17: note: initialize the variable 'jd' to silence this warning
int val, pj, jd, d;
^
= 0
sound/soc/codecs/src4xxx.c:280:3: error: variable 'pj' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
default:
^~~~~~~
sound/soc/codecs/src4xxx.c:288:59: note: uninitialized use occurs here
ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_0F, pj);
^~
sound/soc/codecs/src4xxx.c:223:13: note: initialize the variable 'pj' to silence this warning
int val, pj, jd, d;
^
= 0
3 errors generated.
According to the comment in the default case, other parts of the chip
are still functional without these values so just return 0 in the
default case to avoid using these variables uninitialized.
Link: https://github.com/ClangBuiltLinux/linux/issues/1691
Reported-by: kernel test robot <[email protected]>
Reported-by: "Sudip Mukherjee (Codethink)" <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
---
sound/soc/codecs/src4xxx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/soc/codecs/src4xxx.c b/sound/soc/codecs/src4xxx.c
index a8f143057b41..cf45caa4bf7f 100644
--- a/sound/soc/codecs/src4xxx.c
+++ b/sound/soc/codecs/src4xxx.c
@@ -283,7 +283,7 @@ static int src4xxx_hw_params(struct snd_pcm_substream *substream,
*/
dev_info(component->dev,
"Couldn't set the RCV PLL as this master clock rate is unknown\n");
- break;
+ return 0;
}
ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_0F, pj);
if (ret < 0)
base-commit: 94f072748337424c9cf92cd018532a34db3a5516
--
2.37.2
Hi Matt,
On Tue, Aug 23, 2022 at 08:00:07AM +1000, Matt Flax wrote:
> Hi Nathan,
>
> On 23/8/22 04:31, Nathan Chancellor wrote:
> > Clang warns:
> >
> > sound/soc/codecs/src4xxx.c:280:3: error: variable 'd' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
> > default:
> > ^~~~~~~
> > sound/soc/codecs/src4xxx.c:298:59: note: uninitialized use occurs here
> > ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_11, d);
> > ^
> > sound/soc/codecs/src4xxx.c:223:20: note: initialize the variable 'd' to silence this warning
> > int val, pj, jd, d;
> > ^
> > = 0
>
>
> If you really want to get rid of these warnings, you can use this default
> for the variables :
>
> pj = 0x0;
> jd=0xff;
>
> d = 0xff;
>
> It doesn't really make sense why we would choose to initialise these
> variables, but if you want to silence the preprocessor, then perhaps those
> values. Put a message that defaults are not known nor specified in the data
> sheet and these values are chosen to be unlikely matches of real world
> values - which ensures regmap updates later from an initial unknown chip
> state after refresh.
Okay, I could do something like this?
diff --git a/sound/soc/codecs/src4xxx.c b/sound/soc/codecs/src4xxx.c
index a8f143057b41..db4e280dd055 100644
--- a/sound/soc/codecs/src4xxx.c
+++ b/sound/soc/codecs/src4xxx.c
@@ -280,9 +280,14 @@ static int src4xxx_hw_params(struct snd_pcm_substream *substream,
default:
/* don't error out here,
* other parts of the chip are still functional
+ * Dummy initialize variables to avoid
+ * -Wsometimes-uninitialized from clang.
*/
dev_info(component->dev,
- "Couldn't set the RCV PLL as this master clock rate is unknown\n");
+ "Couldn't set the RCV PLL as this master clock rate is unknown. Chosen regmap values may not match real world values.\n");
+ pj = 0x0;
+ jd = 0xff;
+ d = 0xff;
break;
}
ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_0F, pj);
These warnings need to be eliminated because Linus requires a clean
build as much as possible [1] [2], which has been codified by
CONFIG_WERROR, which is enabled by default with allmodconfig. As a
result, clang allmodconfig builds are broken [3], which you might have
already seen. If there is another way this could be written without
potentially uninitialized variables, I am open to it.
[1]: https://lore.kernel.org/CAHk-=wg-mH-_GYpkhz_psjBWG6ZcjKnPo83fg7YMj_by+-LRTQ@mail.gmail.com/
[2]: https://lore.kernel.org/CAHk-=wi4wyvuXs0SUq-2x=XHxWmJ6jVKRD-WpE0kWgWiqVJNbg@mail.gmail.com/
[3]: https://lore.kernel.org/YwNMUlAmu%2FqCjuva@debian/
> All a bit messy really.
Indeed :/
> > According to the comment in the default case, other parts of the chip
> > are still functional without these values so just return 0 in the
> > default case to avoid using these variables uninitialized.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1691
> > Reported-by: kernel test robot <[email protected]>
> > Reported-by: "Sudip Mukherjee (Codethink)" <[email protected]>
> > Signed-off-by: Nathan Chancellor <[email protected]>
> > ---
> > sound/soc/codecs/src4xxx.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/sound/soc/codecs/src4xxx.c b/sound/soc/codecs/src4xxx.c
> > index a8f143057b41..cf45caa4bf7f 100644
> > --- a/sound/soc/codecs/src4xxx.c
> > +++ b/sound/soc/codecs/src4xxx.c
> > @@ -283,7 +283,7 @@ static int src4xxx_hw_params(struct snd_pcm_substream *substream,
> > */
> > dev_info(component->dev,
> > "Couldn't set the RCV PLL as this master clock rate is unknown\n");
> > - break;
> > + return 0;
>
>
> Don't return here, the rest of the chip is still functional and probably in
> use. Print the dev_info and continue.
I'll send a v2 tomorrow morning (for me at least) if there are no other
comments.
Cheers,
Nathan
That solution looks good.
Matt
On 23/8/22 08:32, Nathan Chancellor wrote:
> Hi Matt,
>
> On Tue, Aug 23, 2022 at 08:00:07AM +1000, Matt Flax wrote:
>> Hi Nathan,
>>
>> On 23/8/22 04:31, Nathan Chancellor wrote:
>>> Clang warns:
>>>
>>> sound/soc/codecs/src4xxx.c:280:3: error: variable 'd' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
>>> default:
>>> ^~~~~~~
>>> sound/soc/codecs/src4xxx.c:298:59: note: uninitialized use occurs here
>>> ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_11, d);
>>> ^
>>> sound/soc/codecs/src4xxx.c:223:20: note: initialize the variable 'd' to silence this warning
>>> int val, pj, jd, d;
>>> ^
>>> = 0
>>
>> If you really want to get rid of these warnings, you can use this default
>> for the variables :
>>
>> pj = 0x0;
>> jd=0xff;
>>
>> d = 0xff;
>>
>> It doesn't really make sense why we would choose to initialise these
>> variables, but if you want to silence the preprocessor, then perhaps those
>> values. Put a message that defaults are not known nor specified in the data
>> sheet and these values are chosen to be unlikely matches of real world
>> values - which ensures regmap updates later from an initial unknown chip
>> state after refresh.
> Okay, I could do something like this?
>
> diff --git a/sound/soc/codecs/src4xxx.c b/sound/soc/codecs/src4xxx.c
> index a8f143057b41..db4e280dd055 100644
> --- a/sound/soc/codecs/src4xxx.c
> +++ b/sound/soc/codecs/src4xxx.c
> @@ -280,9 +280,14 @@ static int src4xxx_hw_params(struct snd_pcm_substream *substream,
> default:
> /* don't error out here,
> * other parts of the chip are still functional
> + * Dummy initialize variables to avoid
> + * -Wsometimes-uninitialized from clang.
> */
> dev_info(component->dev,
> - "Couldn't set the RCV PLL as this master clock rate is unknown\n");
> + "Couldn't set the RCV PLL as this master clock rate is unknown. Chosen regmap values may not match real world values.\n");
> + pj = 0x0;
> + jd = 0xff;
> + d = 0xff;
> break;
> }
> ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_0F, pj);
>
> These warnings need to be eliminated because Linus requires a clean
> build as much as possible [1] [2], which has been codified by
> CONFIG_WERROR, which is enabled by default with allmodconfig. As a
> result, clang allmodconfig builds are broken [3], which you might have
> already seen. If there is another way this could be written without
> potentially uninitialized variables, I am open to it.
>
> [1]: https://lore.kernel.org/CAHk-=wg-mH-_GYpkhz_psjBWG6ZcjKnPo83fg7YMj_by+-LRTQ@mail.gmail.com/
> [2]: https://lore.kernel.org/CAHk-=wi4wyvuXs0SUq-2x=XHxWmJ6jVKRD-WpE0kWgWiqVJNbg@mail.gmail.com/
> [3]: https://lore.kernel.org/YwNMUlAmu%2FqCjuva@debian/
>
>> All a bit messy really.
> Indeed :/
>
>>> According to the comment in the default case, other parts of the chip
>>> are still functional without these values so just return 0 in the
>>> default case to avoid using these variables uninitialized.
>>>
>>> Link: https://github.com/ClangBuiltLinux/linux/issues/1691
>>> Reported-by: kernel test robot <[email protected]>
>>> Reported-by: "Sudip Mukherjee (Codethink)" <[email protected]>
>>> Signed-off-by: Nathan Chancellor <[email protected]>
>>> ---
>>> sound/soc/codecs/src4xxx.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/sound/soc/codecs/src4xxx.c b/sound/soc/codecs/src4xxx.c
>>> index a8f143057b41..cf45caa4bf7f 100644
>>> --- a/sound/soc/codecs/src4xxx.c
>>> +++ b/sound/soc/codecs/src4xxx.c
>>> @@ -283,7 +283,7 @@ static int src4xxx_hw_params(struct snd_pcm_substream *substream,
>>> */
>>> dev_info(component->dev,
>>> "Couldn't set the RCV PLL as this master clock rate is unknown\n");
>>> - break;
>>> + return 0;
>>
>> Don't return here, the rest of the chip is still functional and probably in
>> use. Print the dev_info and continue.
> I'll send a v2 tomorrow morning (for me at least) if there are no other
> comments.
>
> Cheers,
> Nathan
Hi Nathan,
On 23/8/22 04:31, Nathan Chancellor wrote:
> Clang warns:
>
> sound/soc/codecs/src4xxx.c:280:3: error: variable 'd' is used uninitialized whenever switch default is taken [-Werror,-Wsometimes-uninitialized]
> default:
> ^~~~~~~
> sound/soc/codecs/src4xxx.c:298:59: note: uninitialized use occurs here
> ret = regmap_write(src4xxx->regmap, SRC4XXX_RCV_PLL_11, d);
> ^
> sound/soc/codecs/src4xxx.c:223:20: note: initialize the variable 'd' to silence this warning
> int val, pj, jd, d;
> ^
> = 0
If you really want to get rid of these warnings, you can use this
default for the variables :
pj = 0x0;
jd=0xff;
d = 0xff;
It doesn't really make sense why we would choose to initialise these
variables, but if you want to silence the preprocessor, then perhaps
those values. Put a message that defaults are not known nor specified in
the data sheet and these values are chosen to be unlikely matches of
real world values - which ensures regmap updates later from an initial
unknown chip state after refresh. All a bit messy really.
> According to the comment in the default case, other parts of the chip
> are still functional without these values so just return 0 in the
> default case to avoid using these variables uninitialized.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1691
> Reported-by: kernel test robot <[email protected]>
> Reported-by: "Sudip Mukherjee (Codethink)" <[email protected]>
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
> sound/soc/codecs/src4xxx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/soc/codecs/src4xxx.c b/sound/soc/codecs/src4xxx.c
> index a8f143057b41..cf45caa4bf7f 100644
> --- a/sound/soc/codecs/src4xxx.c
> +++ b/sound/soc/codecs/src4xxx.c
> @@ -283,7 +283,7 @@ static int src4xxx_hw_params(struct snd_pcm_substream *substream,
> */
> dev_info(component->dev,
> "Couldn't set the RCV PLL as this master clock rate is unknown\n");
> - break;
> + return 0;
Don't return here, the rest of the chip is still functional and probably
in use. Print the dev_info and continue.