On Fri, Nov 05, 2021 at 01:08:48PM +0000, John Keeping wrote:
> On Thu, Nov 04, 2021 at 02:59:23PM -0700, Nathan Chancellor wrote:
> > A new commit in LLVM causes an error on the use of 'long double' when
> > '-mno-x87' is used, which the kernel does through an alias,
> > '-mno-80387' (see the LLVM commit below for more details around why it
> > does this).
> >
> > drivers/usb/dwc2/hcd_queue.c:1744:25: error: expression requires 'long double' type support, but target 'x86_64-unknown-linux-gnu' does not support it
> > delay = ktime_set(0, DWC2_RETRY_WAIT_DELAY);
> > ^
> > drivers/usb/dwc2/hcd_queue.c:62:34: note: expanded from macro 'DWC2_RETRY_WAIT_DELAY'
> > #define DWC2_RETRY_WAIT_DELAY (1 * 1E6L)
> > ^
> > 1 error generated.
> >
> > This happens due to the use of a 'long double' literal. The 'E6' part of
> > '1E6L' causes the literal to be a 'double' then the 'L' suffix promotes
> > it to 'long double'.
> >
> > There is no visible reason for a floating point value in this driver, as
> > the value is only used as a parameter to a function that expects an
> > integer type. Use USEC_PER_SEC, which is the same integer value as
> > '1E6L', to avoid changing functionality but fix the error.
> >
> > Fixes: 6ed30a7d8ec2 ("usb: dwc2: host: use hrtimer for NAK retries")
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1497
> > Link: https://github.com/llvm/llvm-project/commit/a8083d42b1c346e21623a1d36d1f0cadd7801d83
> > Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> > ---
> > drivers/usb/dwc2/hcd_queue.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c
> > index 89a788326c56..bdf1927e1be1 100644
> > --- a/drivers/usb/dwc2/hcd_queue.c
> > +++ b/drivers/usb/dwc2/hcd_queue.c
> > @@ -59,7 +59,7 @@
> > #define DWC2_UNRESERVE_DELAY (msecs_to_jiffies(5))
> >
> > /* If we get a NAK, wait this long before retrying */
> > -#define DWC2_RETRY_WAIT_DELAY (1 * 1E6L)
> > +#define DWC2_RETRY_WAIT_DELAY (1 * USEC_PER_SEC)
>
> Using USEC_PER_SEC here seems quite weird. This is used as:
>
> delay = ktime_set(0, DWC2_RETRY_WAIT_DELAY);
>
> so the units are nanoseconds.
>
> Maybe NSEC_PER_MSEC would better indicate the intent here?
Yes, that seems reasonable. I will send a v2.
Cheers,
Nathan
