[PATCH] [sound/i2c/cs8427] Fix int to char conversion

[PATCH] [sound/i2c/cs8427] Fix int to char conversion

[Philipp Klocke]

Compiling with clang yields the following warning:

sound/i2c/cs8427.c:140:31: warning: implicit conversion from 'int'
to 'char' changes value from 160 to -96 [-Wconstant-conversion]
    data[0] = CS8427_REG_AUTOINC | CS8427_REG_CORU_DATABUF;
            ~ ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Because CS8427_REG_AUTOINC is defined as 128, it is too big for a
char field.
So change data from char to unsigned char, that it can hold the value.

This patch does not change the generated code.

Signed-off-by: Philipp Klocke <philipp97kl@gmail.com>
---
 sound/i2c/cs8427.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/i2c/cs8427.c b/sound/i2c/cs8427.c
index 2647309bc675..8afa2f888466 100644
--- a/sound/i2c/cs8427.c
+++ b/sound/i2c/cs8427.c
@@ -118,7 +118,7 @@ static int snd_cs8427_send_corudata(struct snd_i2c_device *device,
 	struct cs8427 *chip = device->private_data;
 	char *hw_data = udata ?
 		chip->playback.hw_udata : chip->playback.hw_status;
-	char data[32];
+	unsigned char data[32];
 	int err, idx;
 
 	if (!memcmp(hw_data, ndata, count))
-- 
2.19.1

Re: [PATCH] [sound/i2c/cs8427] Fix int to char conversion

[Takashi Iwai]

On Thu, 18 Oct 2018 12:33:02 +0200,
Philipp Klocke wrote:
> 
> Compiling with clang yields the following warning:
> 
> sound/i2c/cs8427.c:140:31: warning: implicit conversion from 'int'
> to 'char' changes value from 160 to -96 [-Wconstant-conversion]
>     data[0] = CS8427_REG_AUTOINC | CS8427_REG_CORU_DATABUF;
>             ~ ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Because CS8427_REG_AUTOINC is defined as 128, it is too big for a
> char field.
> So change data from char to unsigned char, that it can hold the value.
> 
> This patch does not change the generated code.
> 
> Signed-off-by: Philipp Klocke <philipp97kl@gmail.com>

Applied, thanks.

But at the next time, please put the relevant subsystem MLs to Cc,
and use the proper subject prefix (depending on the subsystem).


Takashi

Re: [PATCH] [sound/i2c/cs8427] Fix int to char conversion

[Takashi Iwai]

On Thu, 18 Oct 2018 15:47:55 +0200,
Philipp K wrote:
> 
> [1  <text/plain; UTF-8 (7bit)>]
> 
> On Thu, Oct 18, 2018, 15:46 Takashi Iwai <tiwai@suse.de> wrote:
> 
>     On Thu, 18 Oct 2018 12:33:02 +0200,
>     Philipp Klocke wrote:
>     >
>     > Compiling with clang yields the following warning:
>     >
>     > sound/i2c/cs8427.c:140:31: warning: implicit conversion from 'int'
>     > to 'char' changes value from 160 to -96 [-Wconstant-conversion]
>     >     data[0] = CS8427_REG_AUTOINC | CS8427_REG_CORU_DATABUF;
>     >             ~ ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
>     >
>     > Because CS8427_REG_AUTOINC is defined as 128, it is too big for a
>     > char field.
>     > So change data from char to unsigned char, that it can hold the value.
>     >
>     > This patch does not change the generated code.
>     >
>     > Signed-off-by: Philipp Klocke <philipp97kl@gmail.com>
>    
>     Applied, thanks.
>    
>     But at the next time, please put the relevant subsystem MLs to Cc,
> 
> Oh sorry I forgot that. Just used the get maintainer script.
> 
>     and use the proper subject prefix (depending on the subsystem).
> 
> What would have been the correct prefix in this case?

In this particular case, I modified the subject to

   ALSA: i2c/cs8427: Fix int to char conversion

The subject prefix usage is case-by-case.  Better to look at the
commits of the relevant file and just follow the convention in
general.


thanks,

Takashi