linux-kernel - [PATCH] clk: qcom: rpmh: Add note about sleep/wake state for BCMs

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Date:   Tue, 17 May 2022 12:09:49 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        patches@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        Alex Elder <elder@...aro.org>,
        Taniya Das <quic_tdas@...cinc.com>
Subject: [PATCH] clk: qcom: rpmh: Add note about sleep/wake state for BCMs

The sleep/wake state doesn't need to be set here because of specific
RPMh behavior that carries over the active state when sleep/wake state
hasn't been modified. Add a note to the code so we aren't tempted to set
the sleep/wake states.

Cc: Alex Elder <elder@...aro.org>
Cc: Taniya Das <quic_tdas@...cinc.com>
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---

This superseedes a previous patch[1] I sent that tried to fix this.

 drivers/clk/qcom/clk-rpmh.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/clk/qcom/clk-rpmh.c b/drivers/clk/qcom/clk-rpmh.c
index aed907982344..c07cab6905cb 100644
--- a/drivers/clk/qcom/clk-rpmh.c
+++ b/drivers/clk/qcom/clk-rpmh.c
@@ -274,6 +274,11 @@ static int clk_rpmh_bcm_send_cmd(struct clk_rpmh *c, bool enable)
 		cmd.addr = c->res_addr;
 		cmd.data = BCM_TCS_CMD(1, enable, 0, cmd_state);
 
+		/*
+		 * Send only an active only state request. RPMh continues to
+		 * use the active state when we're in sleep/wake state as long
+		 * as the sleep/wake state has never been set.
+		 */
 		ret = clk_rpmh_send(c, RPMH_ACTIVE_ONLY_STATE, &cmd, enable);
 		if (ret) {
 			dev_err(c->dev, "set active state of %s failed: (%d)\n",

base-commit: 42226c989789d8da4af1de0c31070c96726d990c
-- 
https://chromeos.dev
[1] https://lore.kernel.org/r/20220412194505.614002-1-swboyd@chromium.org