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@xxxxxxxxxxxxxx/ [2]: https://lore.kernel.org/CAHk-=wi4wyvuXs0SUq-2x=XHxWmJ6jVKRD-WpE0kWgWiqVJNbg@xxxxxxxxxxxxxx/ [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 <lkp@xxxxxxxxx> > > Reported-by: "Sudip Mukherjee (Codethink)" <sudipm.mukherjee@xxxxxxxxx> > > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > > --- > > 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
