ucb1x00 patches

ucb1x00 patches

[Thomas Kunze]

Hi,

I posted these patches at linux-arm-kernel as part of the patchset 
"collie and SA1100 patches".
Could you please comment on them? I'd also like to know you opinion on 
moving ucb1x00-ts.c to
input/drivers/touchscreen.

Regards,
Thomas

ucb1x00 patches

[Lothar Waßmann]

Hi,

Thomas Kunze writes:
> Hi,
> 
> I posted these patches at linux-arm-kernel as part of the patchset 
> "collie and SA1100 patches".
> Could you please comment on them? I'd also like to know you opinion on 
> moving ucb1x00-ts.c to
> input/drivers/touchscreen.
> 
What about the ucb1400_ts.c which is already there?


Lothar Wa?mann
-- 
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___________________________________________________________

ucb1x00 patches

[Marek Vasut]

Dne St 7. ??jna 2009 09:13:22 Lothar Wa?mann napsal(a):
> Hi,
> 
> Thomas Kunze writes:
> > Hi,
> >
> > I posted these patches at linux-arm-kernel as part of the patchset
> > "collie and SA1100 patches".
> > Could you please comment on them? I'd also like to know you opinion on
> > moving ucb1x00-ts.c to
> > input/drivers/touchscreen.
> 
> What about the ucb1400_ts.c which is already there?
> 

I'd be for unifying all the ucb drivers into a single one, but Russell was 
against it iirc.
> 
> Lothar Wa?mann
> 

ucb1x00 patches

[Russell King - ARM Linux]

On Wed, Oct 07, 2009 at 09:56:42AM +0200, Marek Vasut wrote:
> Dne St 7. ??jna 2009 09:13:22 Lothar Wa?mann napsal(a):
> > Hi,
> > 
> > Thomas Kunze writes:
> > > Hi,
> > >
> > > I posted these patches at linux-arm-kernel as part of the patchset
> > > "collie and SA1100 patches".
> > > Could you please comment on them? I'd also like to know you opinion on
> > > moving ucb1x00-ts.c to
> > > input/drivers/touchscreen.
> > 
> > What about the ucb1400_ts.c which is already there?
> > 
> 
> I'd be for unifying all the ucb drivers into a single one, but Russell was 
> against it iirc.

They're different beasts, and I really don't think they should be unified.
They have different register layouts, and different access arrangements,
which need different handling.

The result is that the UCB1200/UCB1300 support gets unnecessarily penalised
when UCB1400 is integrated - instead of merely taking a spinlock and
accessing the register, you have to ensure everything you do is in thread
context, including interrupt handlers.

ucb1x00 patches

[Pavel Machek]

On Wed 2009-10-07 09:12:35, Russell King - ARM Linux wrote:
> On Wed, Oct 07, 2009 at 09:56:42AM +0200, Marek Vasut wrote:
> > Dne St 7. ????jna 2009 09:13:22 Lothar Wa??mann napsal(a):
> > > Hi,
> > > 
> > > Thomas Kunze writes:
> > > > Hi,
> > > >
> > > > I posted these patches at linux-arm-kernel as part of the patchset
> > > > "collie and SA1100 patches".
> > > > Could you please comment on them? I'd also like to know you opinion on
> > > > moving ucb1x00-ts.c to
> > > > input/drivers/touchscreen.
> > > 
> > > What about the ucb1400_ts.c which is already there?
> > > 
> > 
> > I'd be for unifying all the ucb drivers into a single one, but Russell was 
> > against it iirc.
> 
> They're different beasts, and I really don't think they should be unified.
> They have different register layouts, and different access arrangements,
> which need different handling.
> 
> The result is that the UCB1200/UCB1300 support gets unnecessarily penalised
> when UCB1400 is integrated - instead of merely taking a spinlock and
> accessing the register, you have to ensure everything you do is in thread
> context, including interrupt handlers.

Is it that bad?

If sharing makes sense on source-code level, that kind of penalty
should be acceptable. If it makes more eyes on the sources, it will
still be a win.
									Pavel


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

ucb1x00 patches

[Russell King - ARM Linux]

On Sun, Oct 11, 2009 at 02:14:58PM +0200, Pavel Machek wrote:
> On Wed 2009-10-07 09:12:35, Russell King - ARM Linux wrote:
> > On Wed, Oct 07, 2009 at 09:56:42AM +0200, Marek Vasut wrote:
> > > Dne St 7. ????jna 2009 09:13:22 Lothar Wa??mann napsal(a):
> > > > Hi,
> > > > 
> > > > Thomas Kunze writes:
> > > > > Hi,
> > > > >
> > > > > I posted these patches at linux-arm-kernel as part of the patchset
> > > > > "collie and SA1100 patches".
> > > > > Could you please comment on them? I'd also like to know you opinion on
> > > > > moving ucb1x00-ts.c to
> > > > > input/drivers/touchscreen.
> > > > 
> > > > What about the ucb1400_ts.c which is already there?
> > > > 
> > > 
> > > I'd be for unifying all the ucb drivers into a single one, but Russell was 
> > > against it iirc.
> > 
> > They're different beasts, and I really don't think they should be unified.
> > They have different register layouts, and different access arrangements,
> > which need different handling.
> > 
> > The result is that the UCB1200/UCB1300 support gets unnecessarily penalised
> > when UCB1400 is integrated - instead of merely taking a spinlock and
> > accessing the register, you have to ensure everything you do is in thread
> > context, including interrupt handlers.
> 
> Is it that bad?
> 
> If sharing makes sense on source-code level, that kind of penalty
> should be acceptable. If it makes more eyes on the sources, it will
> still be a win.

That argument doesn't always apply.  It is only a win if you have lots
of people testing the code out on *both* chips, so that bugs are
discovered quickly.

The UCB1200/1300 support is stable and good.  Don't break it by totally
changing the way it works just for the sake of a wooley "more eyes must
be good" flimsy argument.