[PATCH v7 0/9] The great interconnecification fixation

Konrad Dybcio
2023-03-08T21:41:13Z

Hi!

v6 -> v7 changelog:
- Rebase on Johan's recent patches

Link to v6: https://lore.kernel.org/r/20230228-topic-qos-v6-0-3c37a349656f@linaro.org

v5 -> v6 changelog:
- Completely rewrite the commit message of [1/9], I realized that there
was actually no issue with the present upstream setups and the only
drivers suffering from ghost votes were.. my own OOT drivers..
As a consequence of that, all fixes tags were dropped and the patch
has been kept, since it was deemed useful for newer SoCs that don't
distinguish ap_owned nodes.

- Change the number of allowed bus_clocks from (0-2 in the previous
revision, 0-inf in the current upstream state) to {0, 2}. Scaling is
only possible with a pair of wake-sleep clocks, but some providers
don't do scaling at all (see 8996 A0NoC, 660 GNoC). Drop the cheeky
-1 / 0 / >0 checks from the previous revision. [7/9]

- bus_clocks are now forced to be named "bus", "bus_a", as there is no
need for variance here - we don't do scaling on non-SMD RPM bus clocks.
[7/9]

- The interface clocks are now only turned on when the associated bus
is running at a non-zero frequency [6/9] instead of being always on
and leaking power

Tested on MSM8996 Kagura, SM6375 PDX225 (OOT), MSM8998 Maple (OOT)

Link to v5: https://lore.kernel.org/linux-arm-msm/20230217-topic-icc-fixes-v5-v5-0-c9a550f9fdb9@linaro.org/

v4 -> v5 changelog:
- Previously the "Always set QoS params on QNoC" contained part of what
should have been included in "make QoS INVALID default".. (very bad)
Fix it!

- Drop negative offset and keep_alive, they will be resubmitted with new
icc driver submissions

- use b4 this time.. hopefully the series gets to everybody now

Link to v4: https://lore.kernel.org/linux-arm-msm/20230214143720.2416762-1-konrad.dybcio@linaro.org/

v3 -> v4 changelog:
- Drop "Always set QoS params on QNoC", it only causes issues.. this
can be investigated another day, as it's not necessary for operation

- Drop "Add a way to always set QoS registers", same as /\

- Add a way (and use it) to have no bus_clocks (the ones we set rate on),
as at least msm8996 has a bus (A0NoC) that doesn't have any and does
all the scaling through RPM requests

- Promote 8996 icc to core_initcall

- Introduce keep_alive (see patch [11/12]) (important!, will be used by at least 6375)

- Allow negative QoS offsets in preparation for introducing 8998 icc [12/12]

Link to v3: https://lore.kernel.org/linux-arm-msm/20230116132152.405535-1-konrad.dybcio@linaro.org/

v2 -> v3 changelog:
- Drop "Don't set QoS params before non-zero bw is requested"

- Rebase on next

- [1/9] ("..make QoS INVALID default.."): remove unused define for
MODE_INVALID_VAL

- Pick up tags

v1 -> v2 changelog:
- reorder "make QoS INVALID default", makes more sense to have it
before "Always set QoS params on QNoC"

- Limit ap_owned-independent QoS setting to QNoC only

- Add new patches for handling the 8996-and-friends clocks situation
and optional BIMC regardless-of-ap_owned QoS programming

[1] https://lore.kernel.org/linux-arm-msm/14e06574-f95e-8960-0243-8c95a1c294e9@linaro.org/T/#m056692bea71d4c272968d5e07afbd9eb07a88123
[2] https://lore.kernel.org/linux-arm-msm/20230110132202.956619-1-konrad.dybcio@linaro.org/

This series grew quite a bit bigger than the previous [1] attempt, so
I decided to also add a cover letter.

Link to v2: [2]

It addresses a few things that were not quite right:

- Setting QoS params before a "real" (non-zero) bandwidth request
makes little sense (since there's no data supposed to flow through
the bus, why would the QoS matter) and (at least newer) downstream
prevents that from happening. Do the same in Patch 1.

- QNoC type buses expect to always have their QoS registers set as long
as there's a non-INVALID QoS mode set; ap_owned is not really a thing
on these anymore, Patch 3 handles that.

- The recent MSM8996 boot fix was done quickly and not quite properly,
leading to possibly setting the aggregate bus rate on "normal"
hardware interface clocks; this series handles that by limiting the
number of bus_clocks to 2 (which is the maximum that makes sense,
anyway) and handling the rest as "intf_clocks", which are required
to access the hardware at the other end. Patches 5-8 take care of
that and Patch 10 reverts the _optional moniker in clk_get_ to make
sure we always have the bus scaling clocks, as they're well, kind
of important ;)

- Similarly to QNoC, BIMC on "newer" (which can be loosely approximated
by "new enough" == "has only BIMC and QNoC hosts") SoCs expects to
always receive QoS programming, whereas BIMC on "older" SoCs cries
like a wild boar and crashes the platform when trying to do so
unconditionally. Patch 9 adds a way to take care of that for newer
SoCs (like SM6375)

- QoS mode INVALID was assumed by developers before to be the default
("I didn't specify any QoS settings, so the driver can't assume I
did.. right? right!?" - wrong, partial struct initialization led to
0 being set and 0 corresponded to QoS mode FIXED). Make it so, as
that's the logical choice. This allows the "Always set QoS params
on QNoC" patch to work without setting tons of what-should-
-obviously-be-the-default values everywhere, as well as fixes older
drivers that set ap_owned = true but left the QoS mode field unset.
Patch 2 cleans that up.

- Some nodes are physically connected over more than one channel
(usually DDR or other high-throughput paths). Patch 4 allows that
to be reflected in calculations. This will be required for at least
MSM8998 and SM6375 (which will be submitted soon after this lands)

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
Konrad Dybcio (9):
interconnect: qcom: rpm: make QoS INVALID default
interconnect: qcom: rpm: Add support for specifying channel num
interconnect: qcom: Sort kerneldoc entries
interconnect: qcom: rpm: Rename icc desc clocks to bus_blocks
interconnect: qcom: rpm: Rename icc provider num_clocks to num_bus_clocks
interconnect: qcom: rpm: Handle interface clocks
interconnect: qcom: icc-rpm: Enforce 2 or 0 bus clocks
interconnect: qcom: rpm: Don't use clk_get_optional for bus clocks anymore
interconnect: qcom: msm8996: Promote to core_initcall

drivers/interconnect/qcom/icc-rpm.c | 89 +++++++++++++++++++++++++------------
drivers/interconnect/qcom/icc-rpm.h | 38 +++++++++++-----
drivers/interconnect/qcom/msm8996.c | 35 +++++++++------
drivers/interconnect/qcom/sdm660.c | 17 +++----
4 files changed, 115 insertions(+), 64 deletions(-)
---
base-commit: fc31900c948610e7b5c2f15fb7795832c8325327
change-id: 20230228-topic-qos-5435cac88d89

Best regards,
--
Konrad Dybcio <konrad.dybcio@linaro.org>