[lkml]   [2018]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Regulator regression in next-20180305

On 03/07/2018 03:10 PM, Mark Brown wrote:
> On Wed, Mar 07, 2018 at 01:57:12PM +0100, Maciej Purski wrote:
>> I'm trying to figure out what is so special about these boards. The only
>> strange thing, that I haven't noticed at first, is that all regulators share
>> a common supply - dummy regulator. It is defined in anatop_regulator.c.
> No, that's a regulator framework thing - the regulator framework will
> use the dummy regulator as a supply when there's nothing described in
> the DT so long as the client doesn't explicitly tell it that the supply
> might be optional.

Ok, thanks for explanation. I think I have found a possibly dangerous scenario,
but I can't see this situation possible in Fabio's case.

Assume, that we have a chain of supplies, consisting of at least 3. Say: A->B->C.

When we're setting voltage on A, we lock it, call balance_voltage(), lock
suppliers and call set_voltage_rdev(). So we have regulators A, B, C locked.
Then set_voltage_rdev() is trying to set voltage of its supply by calling

Now we're on the regulator B. Set_voltage_unlocked() calls balance_voltage(),
which again locks its supplies, if they exist. B's supply is C, so we end up
with having a deadlock on regulator C.

Tony and Fabio, do you find this scenario possible on your boards?

Best regards
Maciej Purski

 \ /
  Last update: 2018-03-07 15:37    [W:0.057 / U:6.272 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site