linux-kernel - [PATCH 3/3] clk: qcom: smd-rpm: Make BI_TCXO

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Message-Id: <20230501-topic-rpmcc_xo_a-v1-3-93f18e47b607@linaro.org>
Date:   Mon, 01 May 2023 14:57:13 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: [PATCH 3/3] clk: qcom: smd-rpm: Make BI_TCXO_AO critical

We should never let go of the active-only XO vote, as otherwise the
RPM may decide that there are no online users and it can be shut down,
resulting in a total, uncontrolled system collapse.

Guarantee this through adding the CLK_IS_CRITICAL flag.

Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
 drivers/clk/qcom/clk-smd-rpm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/qcom/clk-smd-rpm.c b/drivers/clk/qcom/clk-smd-rpm.c
index e00889fddc7b..9649f4644d71 100644
--- a/drivers/clk/qcom/clk-smd-rpm.c
+++ b/drivers/clk/qcom/clk-smd-rpm.c
@@ -439,7 +439,8 @@ static const struct clk_ops clk_smd_rpm_branch_ops = {
 	.recalc_rate	= clk_smd_rpm_recalc_rate,
 };
 
-DEFINE_CLK_SMD_RPM_BRANCH_A(bi_tcxo, QCOM_SMD_RPM_MISC_CLK, 0, 19200000, 0);
+/* Disabling BI_TCXO_AO could gate the root clock source of the entire system. */
+DEFINE_CLK_SMD_RPM_BRANCH_A(bi_tcxo, QCOM_SMD_RPM_MISC_CLK, 0, 19200000, CLK_IS_CRITICAL);
 DEFINE_CLK_SMD_RPM_BRANCH(qdss, QCOM_SMD_RPM_MISC_CLK, 1, 19200000);
 DEFINE_CLK_SMD_RPM_QDSS(qdss, QCOM_SMD_RPM_MISC_CLK, 1);
 DEFINE_CLK_SMD_RPM_BRANCH_A(bimc_freq_log, QCOM_SMD_RPM_MISC_CLK, 4, 1, 0);

-- 
2.40.1