Provide API documentation for rtas_busy_delay_time(), explaining why we
return the same value for 9900 and -2.
Signed-off-by: Nathan Lynch <nath...@linux.ibm.com>
---
arch/powerpc/kernel/rtas.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index d686834fe7f5..4cfe9f93a9cd 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)
{
--
2.31.1
