linux-kernel - [RFC PATCH v1 05/18] i2c: tegra: Fix runtime resume to re-init VI I2C

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Date:   Tue, 9 Jun 2020 23:02:27 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     <skomatineni@...dia.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <frankc@...dia.com>, <hverkuil@...all.nl>,
        <sakari.ailus@....fi>, <robh+dt@...nel.org>,
        <helen.koike@...labora.com>
CC:     <digetx@...il.com>, <sboyd@...nel.org>,
        <gregkh@...uxfoundation.org>, <linux-media@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-i2c@...r.kernel.org>
Subject: [RFC PATCH v1 05/18] i2c: tegra: Fix runtime resume to re-init VI I2C

VI I2C is on host1x bus and is part of VE power domain.

During suspend/resume VE power domain goes through power off/on.

So, controller reset followed by i2c re-initialization is required
after the domain power up.

This patch fixes it.

Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
 drivers/i2c/busses/i2c-tegra.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index dba38a5..650240d 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -293,6 +293,8 @@ struct tegra_i2c_dev {
 	bool is_curr_atomic_xfer;
 };
 
+static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev, bool clk_reinit);
+
 static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
 		       unsigned long reg)
 {
@@ -679,8 +681,22 @@ static int __maybe_unused tegra_i2c_runtime_resume(struct device *dev)
 		goto disable_slow_clk;
 	}
 
+	/*
+	 * VI I2C device is attached to VE power domain which goes through
+	 * power ON/OFF during PM runtime resume/suspend. So, controller
+	 * should go through reset and need to re-initialize after power
+	 * domain ON.
+	 */
+	if (i2c_dev->is_vi) {
+		ret = tegra_i2c_init(i2c_dev, true);
+		if (ret)
+			goto disable_div_clk;
+	}
+
 	return 0;
 
+disable_div_clk:
+	clk_disable(i2c_dev->div_clk);
 disable_slow_clk:
 	if (i2c_dev->slow_clk)
 		clk_disable(i2c_dev->slow_clk);
-- 
2.7.4