linux-kernel - [RFC PATCH v4 01/14] i2c: tegra: Don't mark VI I2C as IRQ safe runtime PM

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Date:   Thu, 23 Jul 2020 16:50:59 -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 v4 01/14] i2c: tegra: Don't mark VI I2C as IRQ safe runtime PM

Tegra VI I2C is part of VE power domain and typically used for
camera usecases.

VE power domain is not always on and is non-IRQ safe. So, IRQ safe
device cannot be attached to a non-IRQ safe domain as it prevents
powering off the PM domain and generic power domain driver will warn.

Current driver marks all I2C devices as IRQ safe and VI I2C device
does not require IRQ safe as it will not be used for atomic transfers.

This patch has fix to make VI I2C as non-IRQ safe.

Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
 drivers/i2c/busses/i2c-tegra.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 1577296..3be1018 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1750,7 +1750,15 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 		goto unprepare_slow_clk;
 	}
 
-	pm_runtime_irq_safe(&pdev->dev);
+	/*
+	 * VI I2C is in VE power domain which is not always on and not
+	 * an IRQ safe. So, IRQ safe device can't be attached to a non-IRQ
+	 * safe domain as it prevents powering off the PM domain.
+	 * Also, VI I2C device don't need to use runtime IRQ safe as it will
+	 * not be used for atomic transfers.
+	 */
+	if (!i2c_dev->is_vi)
+		pm_runtime_irq_safe(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
 	if (!pm_runtime_enabled(&pdev->dev)) {
 		ret = tegra_i2c_runtime_resume(&pdev->dev);
-- 
2.7.4