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| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2023-06-05 15:43:21 +0200 |
|---|---|---|
| committer | Geert Uytterhoeven <geert+renesas@glider.be> | 2023-06-05 15:43:21 +0200 |
| commit | a1b1dd71882f7b9e80e3d1cd4314d17613aafda4 (patch) | |
| tree | ebbdd932ae348fec2178802ce7a716be2d83a7af | |
| parent | cb9a39aacd3d6387b6f1f178a96eadceba90454e (diff) | |
| parent | 7349a69cf3125e92d48e442d9f400ba446fa314f (diff) | |
Merge tag 'iopoll-busy-loop-timeout-tag' into renesas-drivers-for-v6.5
iopoll: Busy loop and timeout improvements
| -rw-r--r-- | include/linux/iopoll.h | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h index 2c8860e406bd..19a7b00baff4 100644 --- a/include/linux/iopoll.h +++ b/include/linux/iopoll.h @@ -53,6 +53,7 @@ } \ if (__sleep_us) \ usleep_range((__sleep_us >> 2) + 1, __sleep_us); \ + cpu_relax(); \ } \ (cond) ? 0 : -ETIMEDOUT; \ }) @@ -73,6 +74,10 @@ * Returns 0 on success and -ETIMEDOUT upon a timeout. In either * case, the last read value at @args is stored in @val. * + * This macro does not rely on timekeeping. Hence it is safe to call even when + * timekeeping is suspended, at the expense of an underestimation of wall clock + * time, which is rather minimal with a non-zero delay_us. + * * When available, you'll probably want to use one of the specialized * macros defined below rather than this macro directly. */ @@ -80,21 +85,30 @@ delay_before_read, args...) \ ({ \ u64 __timeout_us = (timeout_us); \ + s64 __left_ns = __timeout_us * NSEC_PER_USEC; \ unsigned long __delay_us = (delay_us); \ - ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \ - if (delay_before_read && __delay_us) \ + u64 __delay_ns = __delay_us * NSEC_PER_USEC; \ + if (delay_before_read && __delay_us) { \ udelay(__delay_us); \ + if (__timeout_us) \ + __left_ns -= __delay_ns; \ + } \ for (;;) { \ (val) = op(args); \ if (cond) \ break; \ - if (__timeout_us && \ - ktime_compare(ktime_get(), __timeout) > 0) { \ + if (__timeout_us && __left_ns < 0) { \ (val) = op(args); \ break; \ } \ - if (__delay_us) \ + if (__delay_us) { \ udelay(__delay_us); \ + if (__timeout_us) \ + __left_ns -= __delay_ns; \ + } \ + cpu_relax(); \ + if (__timeout_us) \ + __left_ns--; \ } \ (cond) ? 0 : -ETIMEDOUT; \ }) |