On Wed, Apr 01, 2009 at 01:13:46AM -0400, Hugo Villeneuve wrote:
> On Tue, 31 Mar 2009 22:04:46 -0700
> Kevin Hilman <[email protected]> wrote:
> 
> > Hugo Villeneuve <[email protected]> writes:
> > 
> > > On Tue, 31 Mar 2009 21:31:13 -0700
> > > Kevin Hilman <[email protected]> wrote:
> > >
> > >> David Brownell <[email protected]> writes:
> > >> 
> > >> > On Tuesday 31 March 2009, Mark A. Greer wrote:
> > >> >> On Tue, Mar 31, 2009 at 01:43:41PM -0700, David Brownell wrote:
> > >> >> > On Tuesday 31 March 2009, Mark A. Greer wrote:
> > >> >> > > The serial infrastructure is pretty limited WRT this (I have
> > >> >> > > same issue on da830 evm--I only want to use uart2).
> > >> >> > 
> > >> >> > Couldn't you add some kind of "ignore this one" flag to that
> > >> >> > infrastructure, and just have DaVinci use it?
> > >> >> 
> > >> >> Yes and that's probably the right long-term solution.
> > >> >> Problem is that code is used by almost everyone so who knows how
> > >> >> long it'll take to get accepted.
> > >> >
> > >> > Accepted:  should be easy with a sane patch.  No existing
> > >> > driver would be setting that new flag.
> > >> >
> > >> > Used widely:  happens over time, like always.
> > >> 
> > >> We ran into this same problem in OMAP too.  The solution we ame up
> > >> with is to just power-up all UARTs and an inactivity timer disables
> > >> unused UART clocks.
> > >> 
> > >> I tried a solution to this in the 8250 driver, but the bigger
> > >> problem is that the 8250 driver is orphaned.  Patches to add/fix
> > >> features for the 8250 driver go largely ignored on the serial list.
> > >
> > > This all seems overly complicated to me. I don't like the idea of
> > > registering a non-used serial port. I have no problem with having
> > > ttyS0 and ttyS1 if I register UART0 and UART2. Symbolic
> > > links can be used to make things more obvious like
> > > /dev/mydevice -> /dev/ttyS0.
> > 
> > Yes, it is a bit complicated, but your solution leads to complications
> > and confusion as well.
> 
> My solution is there to fix a bug. Before my patch, if you
> registered only UART0 and UART2, it didn't work. I prefer a
> little bit of confusion and to have something bug free for now.
> 
> The real problem seems to be the way that the 8250 driver assigns its
> device numbers. If you disagree with that methodology, then fix the 8250
> driver. Don't use some ugly hacks to avoid the real problem.

That's what David has already suggested but that is only a solution IFF
there is someone on the other end to accept that patch.  As Kevin points
out, there isn't ATM.

Having uart2 known as uart<anything but 2> is unacceptable.
Enabling a uart then disabling is better than having no idea which uart
is which, IMHO.

Mark

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