Re: [PATCH 6/6 V4] input: STMPE touch controller support

From: Rabin VINCENT
Date: Thu Jun 24 2010 - 09:01:40 EST

On Thu, Jun 24, 2010 at 14:42:10 +0200, Luotao Fu wrote:
> On Thu, Jun 24, 2010 at 06:01:53PM +0530, Rabin VINCENT wrote:
> > On Thu, Jun 24, 2010 at 13:13:41 +0200, Luotao Fu wrote:
> > > + ret = stmpe_set_bits(stmpe, STMPE_REG_TSC_FRACTION_Z,
> > > + FRACTION_Z(ts->fraction_z),
> > > + FRACTION_Z(ts->fraction_z));
> >
> > I think your earlier revisions had this same behaviour, but this only
> > writes the bits you are trying to set, and it may be a problem if there
> > are other bits already set in this field. I don't know if this is a
> > concern with this block, but if it is, you can do something like the
> > following to clear out the field before writing:
> >
> This is done intentionally to leave the bits alone which I don't want.
> Most of the registers here are used exclusively for the touchscreen.
> Some others are shared with the ADC. The ADC however doesn't have any
> own configuration and has to go with the configuration of the touch
> screen. Hence it's OK, even probably better not to touch the bits we
> don't need.

I meant something like: let's say you want to change the "count of the
fractional part" (I quote from your platdata). It (the FRACTION_Z
field, I assume) has a default value of (say) 2. Say you want to change
the count to 1. The above write will change it to 3 instead. If this
is really the behaviour you need, it should be OK then.

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