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iopoll: Busy loop and timeout improvements

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Merge tag 'iopoll-busy-loop-timeout-tag' into renesas-clk-for-v6.5

iopoll: Busy loop and timeout improvements
This commit is contained in:
Geert Uytterhoeven 2023-06-05 15:41:13 +02:00
commit f267be7907
1 changed files with 19 additions and 5 deletions
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24
include/linux/iopoll.h
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@ -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; \
})