linux-kernel - [PATCH v1] PM / devfreq: tegra30: Improve initial hardware resetting

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Date:   Sun, 27 Sep 2020 23:51:39 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1] PM / devfreq: tegra30: Improve initial hardware resetting

It's safe to enable the ACTMON clock at any time during driver probing,
even if we don't know the state of hardware, because it's used only for
collecting and processing stats, and interrupt is kept disabled. This
allows us to slightly improve code which performs initial hardware
resetting by making use of a single reset_control_reset() instead of
assert/deassert pair. Secondly, a potential error of the reset-control
API is handled nicely now.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/devfreq/tegra30-devfreq.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index dedd39de7367..f5e74c2ede85 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -822,8 +822,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		return err;
 	}
 
-	reset_control_assert(tegra->reset);
-
 	err = clk_prepare_enable(tegra->clock);
 	if (err) {
 		dev_err(&pdev->dev,
@@ -831,7 +829,11 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
 		return err;
 	}
 
-	reset_control_deassert(tegra->reset);
+	err = reset_control_reset(tegra->reset);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to reset hardware: %d\n", err);
+		goto disable_clk;
+	}
 
 	rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
 	if (rate < 0) {
-- 
2.27.0