xiaoxiang781216 commented on pull request #5782:
URL: https://github.com/apache/incubator-nuttx/pull/5782#issuecomment-1079688130


   @pussuw @jlaitine sorry, I may mix use OpenSBI and RISCV SBI in the 
discussion, so let me clarify what I mean the interface is the spec documented 
here:
   
https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/v1.0.0/riscv-sbi.pdf
   The related function is:
   ```
   Chapter 6. Timer Extension (EID #0x54494D45 "TIME")
   This replaces legacy timer extension (EID #0x00). It follows the new calling 
convention defined in
   v0.2.
   6.1. Function: Set Timer (FID #0)
   struct sbiret sbi_set_timer(uint64_t stime_value)
   Programs the clock for next event after stime_value time. stime_value is in 
absolute time. This
   function must clear the pending timer interrupt bit as well.
   If the supervisor wishes to clear the timer interrupt without scheduling the 
next timer event, it can
   either request a timer interrupt infinitely far into the future (i.e., 
(uint64_t)-1), or it can instead mask
   the timer interrupt by clearing sie.STIE CSR bit.
   ```
   sbi_set_timer is more flexible than riscv_sbi_ack_timer since 
riscv_sbi_ack_timer can't implement tickless mode which is very important for 
all battery powered device.


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