Re: [PATCH v7 6/9] interconnect: qcom: rpm: Handle interface clocks

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Hi Konrad,

Thank you for working on this and sorry about jumping a bit late into
the discussion.

On 8.03.23 23:40, Konrad Dybcio wrote:
Some (but not all) providers (or their specific nodes) require
specific clocks to be turned on before they can be accessed. Failure
to ensure that results in a seemingly random system crash (which
would usually happen at boot with the interconnect driver built-in),
resulting in the platform not booting up properly.

These "interface" clocks seem to be used only to program QoS for the
respective ip block (eg ufs). So if we don't program QoS, there should
be no crashes, right?

I believe that in downstream they defer setting QoS until the first
non-zero bandwidth request because of drivers that probe asynchronously
or there is some firmware booting involved (IPA maybe). And bad stuff
might happen if we touch the clock while the firmware is still booting.
So setting the QoS on the first non-zero bandwidth request might not be
a bad idea. Such nodes should probably be also excluded from sync_state
by implementing get_bw() to return 0 bandwidth.

BR,
Georgi


Limit the number of bus_clocks to 2 (which is the maximum that SMD
RPM interconnect supports anyway) and handle non-scaling clocks
separately. Update MSM8996 and SDM660 drivers to make sure they do
not regress with this change.

This unfortunately has to be done in one patch to prevent either
compile errors or broken bisect.

Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
---
  drivers/interconnect/qcom/icc-rpm.c | 52 ++++++++++++++++++++++++++++++-------
  drivers/interconnect/qcom/icc-rpm.h | 14 ++++++++--
  drivers/interconnect/qcom/msm8996.c | 22 +++++++---------
  drivers/interconnect/qcom/sdm660.c  | 16 +++++-------
  4 files changed, 70 insertions(+), 34 deletions(-)

[..]




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