linux-kernel - Re: [PATCH 5/6] i2c: tegra: Add runtime power-management support

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Date:	Thu, 11 Aug 2016 20:31:02 +0530
From:	Laxman Dewangan <ldewangan@...dia.com>
To:	Jon Hunter <jonathanh@...dia.com>,
	Wolfram Sang <wsa@...-dreams.de>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>
CC:	<linux-i2c@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/6] i2c: tegra: Add runtime power-management support


On Thursday 11 August 2016 03:46 PM, Jon Hunter wrote:
> Update the Tegra I2C driver to use runtime PM and move the code in the
> tegra_i2c_clock_enable/disable() functions to the PM runtime resume and
> suspend callbacks, respectively.
>
> Note that given that CONFIG_PM is not mandatory for Tegra, if CONFIG_PM
> is not enabled and so runtime PM is not enabled, ensure that the I2C
> clocks are turned on during probe and kept on by calling the resume
> callback directly.
>
> In the function tegra_i2c_init(), the variable 'err' does not need to be
> initialised to zero in tegra_i2c_init() because it is initialised when
> pm_runtime_get_sync() is called. Furthermore, to ensure we only return 0
> from tegra_i2c_init(), it is necessary to re-initialise 'err' to 0 after
> a successful call to pm_runtime_get_sync() because it can return a
> positive value on success. However, alternatively re-initialise 'err' by
> using the return value of the function tegra_i2c_flush_fifos() because
> it can only be 0 or -ETIMEDOUT.
>
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>
Acked-by: Laxman Dewangan <ldewangan@...dia.com>