Re: [PATCH v1] i2c: tegra: Remove suspend-resume

[Wolfram Sang]

On Mon, May 14, 2018 at 12:13:47AM +0300, Dmitry Osipenko wrote:
> Nothing prevents I2C clients to access I2C while Tegra's driver is being
> suspended, this results in -EBUSY error returned to the clients and that
> may have unfortunate consequences. In particular this causes problems
> for the TPS6586x MFD driver which emits hundreds of "failed to read
> interrupt status" error messages on resume from suspend. This happens if
> TPS6586X is used to wake system from suspend by the expired RTC alarm
> timer because TPS6586X is an I2C device driver and its IRQ handler reads
> the status register while Tegra's I2C driver is suspended, i.e. just after
> kernel enabled IRQ's during of resume-from-suspend process.
> 
> Note that the removed tegra_i2c_resume() invoked tegra_i2c_init() which
> performs HW reset. That seems was also not entirely correct because moving
> tegra_i2c_resume to an earlier stage of resume-from-suspend process causes
> I2C transfer to fail in the case of TPS6586X. It is fine to remove the
> HW-reinitialization for now because it should be only needed in a case of
> using lowest power-mode during suspend, which upstream kernel doesn't
> support.
> 
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>

Applied to for-next, thanks!

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