linux-kernel - Re: [PATCH 3/5] mfd: ti_am335x_tscadc: Don't read back REG

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Date:	Mon, 6 Jan 2014 10:10:43 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Zubair Lutfullah <zubair.lutfullah@...il.com>,
	Felipe Balbi <balbi@...com>, linux-iio@...r.kernel.org,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] mfd: ti_am335x_tscadc: Don't read back REG_SE

On Mon, Jan 06, 2014 at 09:35:25AM +0000, Lee Jones wrote:
> On Thu, 19 Dec 2013, Sebastian Andrzej Siewior wrote:
> 
> > The purpose of reg_se_cache has been defeated. It should avoid the
> > read-back of the register to avoid the latency and the fact that the
> > bits are reset to 0 after the individual conversation took place.
> > 
> > The reason why this is required like this to work, is that read-back of
> > the register removes the bits of the ADC so they do not start another
> > conversation after the register is re-written from the TSC side for the
> > update.
> > To avoid the not required read-back I introduce a "set once" variant which
> > does not update the cache mask. After the conversation completes, the
> > bit is removed from the SE register anyway and we don't plan a new
> > conversation "any time soon". The current set function is renamed to
> > set_cache to distinguish the two operations.
> > This is a small preparation for a larger sync-rework.
> > 
> > Acked-by: Lee Jones <lee.jones@...aro.org>
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> > ---
> >  drivers/iio/adc/ti_am335x_adc.c           |  4 ++--
> >  drivers/input/touchscreen/ti_am335x_tsc.c |  4 ++--
> 
> Just need Dmitry's Ack now.

Well, that has nothing to do with input per se but rather inner workings
of the device. But yes, FWIW:

Acked-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

Thanks.

-- 
Dmitry
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