[alsa-devel] [PATCH 0/7] ALSA: USB-audio: Support Zoom R16 playback

[Takashi Iwai]

On Fri, 16 Oct 2015 09:22:01 +0200,
Ricard Wanderlof wrote:
> 
> 
> On Fri, 16 Oct 2015, Takashi Iwai wrote:
> 
> > The changes look OK, the only point to be fixed would be the use of
> > __le32 for a variable as kbuild bot suggested.
> 
> Ok, however I interpreted the kbuild warning as that the output type of 
> cpu_to_le32() is the same as the input type, so the resulting 'unsigned 
> int' might not necessarily fit into the target u32 variable. So when the 
> input type is an unsigned int, it should be cast to an u32 to be the same 
> as the output type.
> 
> I looked around in various parts of the kernel code to see how 
> cpu_to_le32() was used, and most cases have an u32 as the argument, and 
> when not, the argument is simply cast to u32, i.e.
> 
> unsigned int length;
> u32 packet_length = cpu_to_le32((u32)length);

No, other way round: the problem is that packet_length is declared as
u32 while it should be __le32.  The length variable must be CPU
endian, of course, as you apply C arithmetic.


Takashi