[RFC,0/2] clk: meson: g12a: handle clock hw changes while in suspend

Message

Neil Armstrong Sept. 19, 2019, 10:25 a.m. UTC

This serie aime to support when the suspend/resume firmware alters the
clock tree, leading to an incorrect representation of the clock tree
after a resume from suspend-to-mem.

For the Amlogic G12A/G12B/SM1 case, the SCPI firmware handling suspend
alters the CPU clock tree in various ways.

Since we know which part of the tree is possibly altered, we introduce here
the clk_invalidate_rate() function that will rebuild the tree from the
hardware registers in case parents and dividers have changed.

Finally we call clk_invalidate_rate() from a new resume callback to refresh
the CPU clock tree after a resume.

With the clock tree refreshed, CCF can now handle the new clock tree
configuration and avoid crashing the system on further DVFS set_rates.

Neil Armstrong (2):
  clk: introduce clk_invalidate_rate()
  clk: meson: g12a: add suspend-resume hooks

 drivers/clk/clk.c        | 70 +++++++++++++++++++++++++++++++++++++++
 drivers/clk/meson/g12a.c | 71 +++++++++++++++++++++++++++++++++++-----
 include/linux/clk.h      | 13 ++++++++
 3 files changed, 146 insertions(+), 8 deletions(-)

Comments

Kevin Hilman Sept. 26, 2019, 8:46 p.m. UTC | #1

Neil Armstrong <[e-mail]> writes:

> This serie aime to support when the suspend/resume firmware alters the
> clock tree, leading to an incorrect representation of the clock tree
> after a resume from suspend-to-mem.
>
> For the Amlogic G12A/G12B/SM1 case, the SCPI firmware handling suspend
> alters the CPU clock tree in various ways.
>
> Since we know which part of the tree is possibly altered, we introduce here
> the clk_invalidate_rate() function that will rebuild the tree from the
> hardware registers in case parents and dividers have changed.
>
> Finally we call clk_invalidate_rate() from a new resume callback to refresh
> the CPU clock tree after a resume.
>
> With the clock tree refreshed, CCF can now handle the new clock tree
> configuration and avoid crashing the system on further DVFS set_rates.

For clarification, does this series work without the other proposed
fixes[1]?  or is this dependent on that?

Kevin

[1] https://lore.kernel.org/linux-amlogic/[e-mail]/

Neil Armstrong Sept. 27, 2019, 6:38 a.m. UTC | #2

On 26/09/2019 22:46, Kevin Hilman wrote:
> Neil Armstrong <[e-mail]> writes:
> 
>> This serie aime to support when the suspend/resume firmware alters the
>> clock tree, leading to an incorrect representation of the clock tree
>> after a resume from suspend-to-mem.
>>
>> For the Amlogic G12A/G12B/SM1 case, the SCPI firmware handling suspend
>> alters the CPU clock tree in various ways.
>>
>> Since we know which part of the tree is possibly altered, we introduce here
>> the clk_invalidate_rate() function that will rebuild the tree from the
>> hardware registers in case parents and dividers have changed.
>>
>> Finally we call clk_invalidate_rate() from a new resume callback to refresh
>> the CPU clock tree after a resume.
>>
>> With the clock tree refreshed, CCF can now handle the new clock tree
>> configuration and avoid crashing the system on further DVFS set_rates.
> 
> For clarification, does this series work without the other proposed
> fixes[1]?  or is this dependent on that?
> 
> Kevin
> 
> [1] https://lore.kernel.org/linux-amlogic/[e-mail]/
> 

These are independent, but you'll need both to have suspend/resume fully working.

Neil