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| author | Nathan Lynch <nathanl@linux.ibm.com> | 2021-11-17 00:02:59 -0600 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-11-25 11:25:33 +1100 |
| commit | dd5cde457a5eb77088d1d9eecface47c0563cd43 (patch) | |
| tree | c89405b5dcbdef52485f5dd2275e66cdcb336f48 | |
| parent | 38f7b7067dae0c101be573106018e8af22a90fdf (diff) | |
| download | lwn-dd5cde457a5eb77088d1d9eecface47c0563cd43.tar.gz lwn-dd5cde457a5eb77088d1d9eecface47c0563cd43.zip | |
powerpc/rtas: rtas_busy_delay_time() kernel-doc
Provide API documentation for rtas_busy_delay_time(), explaining why we
return the same value for 9900 and -2.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211117060259.957178-3-nathanl@linux.ibm.com
| -rw-r--r-- | arch/powerpc/kernel/rtas.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 048599a68834..733e6ef36758 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -492,8 +492,25 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) } EXPORT_SYMBOL(rtas_call); -/* For RTAS_BUSY (-2), delay for 1 millisecond. For an extended busy status - * code of 990n, perform the hinted delay of 10^n (last digit) milliseconds. +/** + * rtas_busy_delay_time() - From an RTAS status value, calculate the + * suggested delay time in milliseconds. + * + * @status: a value returned from rtas_call() or similar APIs which return + * the status of a RTAS function call. + * + * Context: Any context. + * + * Return: + * * 100000 - If @status is 9905. + * * 10000 - If @status is 9904. + * * 1000 - If @status is 9903. + * * 100 - If @status is 9902. + * * 10 - If @status is 9901. + * * 1 - If @status is either 9900 or -2. This is "wrong" for -2, but + * some callers depend on this behavior, and the worst outcome + * is that they will delay for longer than necessary. + * * 0 - If @status is not a busy or extended delay value. */ unsigned int rtas_busy_delay_time(int status) { |