[PATCH 2/3] delay: Add explanation of udelay() inaccuracy

2017-01-27 Thread John Stultz
From: Russell King There seems to be some misunderstanding that udelay() and friends will always guarantee the specified delay. This is a false understanding. When udelay() is based on CPU cycles, it can return early for many reasons which are detailed by Linus'

[PATCH 2/3] delay: Add explanation of udelay() inaccuracy

2017-01-27 Thread John Stultz
From: Russell King There seems to be some misunderstanding that udelay() and friends will always guarantee the specified delay. This is a false understanding. When udelay() is based on CPU cycles, it can return early for many reasons which are detailed by Linus' reply to me in a thread in 2011: