[alsa-devel] [PATCH 2/2] sis7019: add support for pre-2.6 kernels

[Clemens Ladisch]

Dave Dillow wrote:
> On Mon, 2007-12-10 at 08:53 +0100, Clemens Ladisch wrote:
> > Dave Dillow wrote:
> > > The sis7019 driver uses __ffs(), which is available in 2.6 kernels, but
> > > not in most earlier ones. This patches the driver to use a local version
> > > assembly version, as the hardware is SiS 55x only (i486/Pentium-ish).
> > > 
> > > ++#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
> > > ++static inline unsigned long sis_ffs(unsigned long word)
> > > ++{
> > > ++	__asm__("bsfl %1,%0"
> > > ++		:"=r" (word)
> > > ++		:"rm" (word));
> > > ++	return word;
> > > ++}
> > > ++#endif
> > 
> > This should go into alsa-driver/include/adriver.h.
> 
> I'm not sure -- there's no other inline assembly there, and if I provide
> an x86 _ffs() fallback, then it'll break on other architectures...

It won't break unless another driver actually uses __ffs(), and then we
can still add a generic implementation.


Regards,
Clemens