On Mon, 2021-01-11 at 09:27 +0800, Can Guo wrote:
>
> If accessing sysfs nodes, which triggers a UFS UPIU request to
> read/write UFS device descriptors during shutdown flow, there is
> only
> one issue that sysfs node access failure since UFS device and LINK
> has
> been shutdown. Strictly speaking, the failure comes after
> ufshcd_set_dev_pwr_mode().
>
> __ufshcd_query_descriptor: opcode 0x01 for idn 0 failed, index
> 0,
> err = -11
You misunderstood it again. You are expecting a simple query cmd
error.
But what really matters are NoC issues[1] and OCP[2]. And
while/after
UFS
shutting down, either of them may happen.
[1] When a un-clocked register access issue happens, we call it a
NoC
issue,
meaning you are tring to access a register when clocks are disabled.
This
leads to system CRASH.
OK, let it simple, share this kind of crash log becuase of access sysfs
node in the shutdown flow.
[2] OCP is over current protection. While UFS shutting down, you may
have put UFS regulators to LPM. After that, if you are still trying
to
talk to UFS, OCP can happen on VCCQ/VCCQ2. This leads to system
CRASH
too.
the same as above, share the crash log.
>
> Since the shutdown is oneway process, this failure is not big
> issue. If
> you meant to avoid this failure for unsafe shutdown, I agree with
> you,
> But for the race issue, I don't know.
>
Easy for you to say. System crash is a big issue to any SoC vendors
I
belive.
indeed, crash is serious issue, share the log.
Thanks,
Bean
Can Guo.