linux-kernel - [PATCH 0/4] mailbox: qcom-apcs-ipc: Avoid circular dependency with clock controller

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Message-Id: <20250506-qcom-apcs-mailbox-cc-v1-0-b54dddb150a5@linaro.org>
Date: Tue, 06 May 2025 15:10:07 +0200
From: Stephan Gerhold <stephan.gerhold@...aro.org>
To: Jassi Brar <jassisinghbrar@...il.com>, 
 Bjorn Andersson <andersson@...nel.org>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-clk@...r.kernel.org, Georgi Djakov <djakov@...nel.org>, 
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH 0/4] mailbox: qcom-apcs-ipc: Avoid circular dependency with
 clock controller

The APCS "global" node in the device tree currently combines two distinct
use cases in a single device tree node: a mailbox to communicate with other
remoteprocs in the system, and a clock for controlling the CPU frequency.

These two use cases have unavoidable circular dependencies: the mailbox is
needed as early as possible during boot to start controlling shared
resources like clocks and power domains, while the clock controller needs
one of these shared clocks as its parent. Currently, there is no way to
distinguish these two use cases for generic mechanisms like fw_devlink.

Break up the circular dependency chain in the device tree by separating the
clock controller into a separate child node.

The patches in this series should be merged together in one tree to avoid
potential bisect problems. Given the majority of the changes is in the
mailbox subsystem and the QC clock drivers only have trivial 1-line
changes, I propose merging all of these through the mailbox subsystem.

@Bjorn: If this sounds good to you, could you provide an Acked-by for the
two "clk: qcom:" patches?

Signed-off-by: Stephan Gerhold <stephan.gerhold@...aro.org>
---
Stephan Gerhold (4):
      dt-bindings: mailbox: qcom,apcs: Add separate node for clock-controller
      mailbox: qcom-apcs-ipc: Assign OF node to clock controller child device
      clk: qcom: apcs-msm8916: Obtain clock from own OF node
      clk: qcom: apcs-sdx55: Obtain clock from own OF node

 .../bindings/mailbox/qcom,apcs-kpss-global.yaml    | 169 ++++++++++++++-------
 drivers/clk/qcom/apcs-msm8916.c                    |   2 +-
 drivers/clk/qcom/apcs-sdx55.c                      |   2 +-
 drivers/mailbox/qcom-apcs-ipc-mailbox.c            |  16 +-
 4 files changed, 132 insertions(+), 57 deletions(-)
---
base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
change-id: 20250505-qcom-apcs-mailbox-cc-6e292bb6d40e

Best regards,
-- 
Stephan Gerhold <stephan.gerhold@...aro.org>