On Thu, Nov 4, 2021 at 2:59 PM Nathan Chancellor [off-list ref] 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@kernel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <redacted>

-- 
Thanks,
~Nick Desaulniers